feat: Add Projects V2 resources

[TorinAsakura]

Resolves #2918

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Before the change?

• Managing Projects V2 projects, custom fields, item values, and project links requires a separate raw GraphQL layer outside the provider.

After the change?

• Projects V2 projects, custom fields (including iteration fields), items, field values, repository links, and team links can be managed as Terraform resources.
• The resources use the provider's existing official GitHub GraphQL client because the REST client does not expose the required Projects V2 mutations.
• The GraphQL lifecycle is covered by mocked contract tests, and each resource includes an example and generated documentation.
• This PR was largely generated with AI assistance, then reviewed against the live GitHub GraphQL schema and tested locally.

Pull request checklist

• Schema migrations have been created if needed (example)
• Tests for the changes have been added (for bug fixes / features)
• Docs have been reviewed and added / updated if needed (for bug fixes / features)

Does this introduce a breaking change?

Please see our docs on breaking changes to help!

• Yes
• No

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P.S: AlmostDDDPowered ^^

[github-actions]

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[Copilot]

Pull request overview

These provider review instructions are being used.

Findings

• HIGH: Multi-step creation failures can leave unmanaged Projects V2 projects or items.
• MEDIUM: Read-after-write calls risk stale failures and excess API usage; repository links are not rename-safe.
• MEDIUM: Schema descriptions and diagnostic validators are missing, and mocked tests do not validate GraphQL variables.

Adds six Terraform resources for managing GitHub Projects V2 through GraphQL.

Changes:

• Adds projects, fields, items, field values, repository links, and team links.
• Introduces application use cases and GraphQL gateways.
• Adds examples, generated documentation, and mocked tests.

Reviewed changes

Copilot reviewed 101 out of 101 changed files in this pull request and generated 19 comments.

Show a summary per file

File	Description
templates/resources/team_project.md.tmpl	Team-link documentation template
templates/resources/project.md.tmpl	Project documentation template
templates/resources/project_repository.md.tmpl	Repository-link documentation template
templates/resources/project_item.md.tmpl	Item documentation template
templates/resources/project_item_field_value.md.tmpl	Field-value documentation template
templates/resources/project_field.md.tmpl	Field documentation template
internal/infrastructure/providers/github/projects/v2/team/link/mapper.go	Maps team links
internal/infrastructure/providers/github/projects/v2/team/link/gateway.go	Team-link GraphQL gateway
internal/infrastructure/providers/github/projects/v2/team/link/dto.go	Team GraphQL DTOs
internal/infrastructure/providers/github/projects/v2/repository/link/mapper.go	Maps repository links
internal/infrastructure/providers/github/projects/v2/repository/link/gateway.go	Repository-link gateway
internal/infrastructure/providers/github/projects/v2/repository/link/dto.go	Repository GraphQL DTOs
internal/infrastructure/providers/github/projects/v2/project/mapper.go	Maps projects
internal/infrastructure/providers/github/projects/v2/project/mapper_test.go	Tests project mapping
internal/infrastructure/providers/github/projects/v2/project/gateway.go	Project GraphQL gateway
internal/infrastructure/providers/github/projects/v2/project/dto.go	Project GraphQL DTOs
internal/infrastructure/providers/github/projects/v2/item/mapper.go	Maps project items
internal/infrastructure/providers/github/projects/v2/item/gateway.go	Item GraphQL gateway
internal/infrastructure/providers/github/projects/v2/item/field/value/mapper.go	Maps field values
internal/infrastructure/providers/github/projects/v2/item/field/value/mapper_test.go	Tests value mapping
internal/infrastructure/providers/github/projects/v2/item/field/value/gateway.go	Field-value gateway
internal/infrastructure/providers/github/projects/v2/item/field/value/dto.go	Field-value DTOs
internal/infrastructure/providers/github/projects/v2/item/dto.go	Item GraphQL DTOs
internal/infrastructure/providers/github/projects/v2/graphql/not_found.go	Normalizes not-found errors
internal/infrastructure/providers/github/projects/v2/graphql/not_found_test.go	Tests error normalization
internal/infrastructure/providers/github/projects/v2/graphql/date.go	Parses GraphQL dates
internal/infrastructure/providers/github/projects/v2/field/mapper.go	Maps custom fields
internal/infrastructure/providers/github/projects/v2/field/mapper_test.go	Tests field mapping
internal/infrastructure/providers/github/projects/v2/field/gateway.go	Field GraphQL gateway
internal/infrastructure/providers/github/projects/v2/field/dto.go	Field GraphQL DTOs
internal/application/projects/team/link/use-cases/get.go	Gets team links
internal/application/projects/team/link/use-cases/detach.go	Detaches team links
internal/application/projects/team/link/use-cases/attach.go	Attaches team links
internal/application/projects/team/link/use-cases/attach_test.go	Tests team attachment
internal/application/projects/team/link/store.go	Team-link store contract
internal/application/projects/team/link/result.go	Team-link models
internal/application/projects/repository/link/use-cases/get.go	Gets repository links
internal/application/projects/repository/link/use-cases/detach.go	Detaches repository links
internal/application/projects/repository/link/use-cases/attach.go	Attaches repository links
internal/application/projects/repository/link/use-cases/attach_test.go	Tests repository attachment
internal/application/projects/repository/link/store.go	Repository-link store contract
internal/application/projects/repository/link/result.go	Repository-link models
internal/application/projects/project/use-cases/update.go	Updates projects
internal/application/projects/project/use-cases/get.go	Gets projects
internal/application/projects/project/use-cases/delete.go	Deletes projects
internal/application/projects/project/use-cases/create.go	Creates projects
internal/application/projects/project/use-cases/create_test.go	Tests project creation
internal/application/projects/project/store.go	Project store contract
internal/application/projects/project/result.go	Project models
internal/application/projects/not_found.go	Defines not-found sentinel
internal/application/projects/item/use-cases/restore.go	Restores items
internal/application/projects/item/use-cases/remove.go	Removes items
internal/application/projects/item/use-cases/get.go	Gets items
internal/application/projects/item/use-cases/archive.go	Archives items
internal/application/projects/item/use-cases/add.go	Adds items
internal/application/projects/item/use-cases/add_test.go	Tests item addition
internal/application/projects/item/store.go	Item store contract
internal/application/projects/item/result.go	Item models
internal/application/projects/item/field/value/use-cases/set.go	Sets field values
internal/application/projects/item/field/value/use-cases/set_test.go	Tests value setting
internal/application/projects/item/field/value/use-cases/get.go	Gets field values
internal/application/projects/item/field/value/use-cases/clear.go	Clears field values
internal/application/projects/item/field/value/store.go	Value store contract
internal/application/projects/item/field/value/result.go	Field-value models
internal/application/projects/field/use-cases/update.go	Updates fields
internal/application/projects/field/use-cases/get.go	Gets fields
internal/application/projects/field/use-cases/delete.go	Deletes fields
internal/application/projects/field/use-cases/create.go	Creates fields
internal/application/projects/field/use-cases/create_test.go	Tests field creation
internal/application/projects/field/store.go	Field store contract
internal/application/projects/field/result.go	Field models
github/resource_github_team_project.go	Implements team-link resource
github/resource_github_team_project_test.go	Tests team-link resource
github/resource_github_project.go	Implements project resource
github/resource_github_project_test.go	Tests project resource
github/resource_github_project_repository.go	Implements repository-link resource
github/resource_github_project_repository_test.go	Tests repository links
github/resource_github_project_item.go	Implements item resource
github/resource_github_project_item_test.go	Tests item resource
github/resource_github_project_item_field_value.go	Implements field-value resource
github/resource_github_project_item_field_value_test.go	Tests field values
github/resource_github_project_field.go	Implements field resource
github/resource_github_project_field_test.go	Tests field resource
github/provider.go	Registers new resources
github/provider_project_v2_test.go	Tests registration and dates
github/project_v2_test_helpers_test.go	Provides GraphQL test server
github/project_v2_schema.go	Adds schema conversion helpers
github/project_v2_provider.go	Accesses provider metadata
github/project_v2_date.go	Validates Projects V2 dates
examples/resources/team_project/example_1.tf	Shows team linking
examples/resources/project/example_1.tf	Shows project creation
examples/resources/project_repository/example_1.tf	Shows repository linking
examples/resources/project_item/example_1.tf	Shows item addition
examples/resources/project_item_field_value/example_1.tf	Shows value assignment
examples/resources/project_field/example_1.tf	Shows field creation
docs/resources/team_project.md	Generated team-link docs
docs/resources/project.md	Generated project docs
docs/resources/project_repository.md	Generated repository-link docs
docs/resources/project_item.md	Generated item docs
docs/resources/project_item_field_value.md	Generated field-value docs
docs/resources/project_field.md	Generated field docs