chore(cli): migrate @fern-api/cli-migrations to use CliError

[FedeZara]

Description

Migrates @fern-api/cli-migrations to use explicit CliError error codes on every failAndThrow / failWithoutThrowing call site.

This is one of the package migration PRs that follow the error classification system introduced in #14749.

Changes Made

Assigned typed error codes across 36 files in packages/cli/cli-migrations/src/, covering every failAndThrow and failWithoutThrowing invocation. Also added missing CliError imports to all migration files that reference CliError.Code.

Error codes used

Code	Usage
CONFIG_ERROR	Fern directory not found, generators.yml missing/invalid, missing configuration
PARSE_ERROR	Failed YAML migrations, malformed schema objects, invalid type/union/error maps
VALIDATION_ERROR	Invalid migration targets, schema validation during upgrades

Files touched (grouped by area)

• Run migrations: runMigrations.ts
• Early migrations (0.0.x): discriminant/, union-single-property-key/, add-mode-to-draft-generators/, remove-inline-error-declarations/, add-publishing-to-release-generators/, rename-alias-key-to-type/, add-error-discriminant/, add-generator-groups/, add-error-discrimination-config/
• Mid migrations (0.1.x-0.9.x): add-inline-requests/, add-value-key-to-type-examples/, change-services-key-to-service/, move-service-docs-to-top-level/, require-generators-yml/, use-generators-yml-specs/, add-path-parameter-order-setting/, add-suffix-to-docs-domain/
• Late migrations (1.0+): update-settings-defaults/ (1.0.0 and 2.0.0-rc0), migrate-deprecated-generator-api-settings/, enable-smart-casing/, update-directory-structure/

Testing

• Existing tests pass (pnpm test, excluding e2e and pre-existing environment failures)

[FedeZara]

• chore(cli): migrate @fern-api/cli-migrations to use CliError #14991 👈 (View in Graphite)
• main

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