Add GET templates under v3

[jzbahrai]

Summary | Résumé

Added a GET template method. This method currently exists, but we want to gate it behind APIKEYs with manage_template permissions.

Test instructions | Instructions pour tester la modification

1. Test getting a template locally
2. If you aren't use a the new API key with a manage template permission, you should get a forbidden error
3. Otherwise the template should return
4. Test both scenarios

[Copilot]

Pull request overview

Adds a new authenticated /v3/template/<template_id> GET endpoint intended to expose template details only to API keys with manage_templates permission.

Changes:

• Registers a new v3 template blueprint and GET template route.
• Adds serialization for template metadata including category, folder, process type, and archived state.
• Adds v3 endpoint tests and API-key fixtures for permission-gated access.

Reviewed changes

Copilot reviewed 5 out of 8 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
app/__init__.py	Registers the v3 template blueprint.
app/v3/__init__.py	Adds v3 package marker.
app/v3/template/__init__.py	Defines the v3 template blueprint and error handlers.
app/v3/template/get_template.py	Implements the v3 GET template endpoint and response serialization.
tests/app/conftest.py	Adds API-key fixtures with and without template management permission.
tests/app/v3/__init__.py	Adds v3 test package marker.
tests/app/v3/template/__init__.py	Adds v3 template test package marker.
tests/app/v3/template/test_get_template.py	Adds endpoint behavior and permission tests.

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[jzbahrai]

the formatter make format is forcing this :/