🌩️ feat: CloudFront CDN File Strategy (#12193)

* 🌩️ feat: CloudFront CDN File Strategy + signed cookies

Squashed from PR #12193:
- feat(storage): add CloudFront CDN file strategy
- feat(auth): add CloudFront signed cookie support

Note: package.json/package-lock.json dependency additions are intentionally
omitted from this commit and will be re-added via `npm install` after rebase
to avoid lock-file merge conflicts. The two new peer deps that need to be
re-installed are:
  - @aws-sdk/client-cloudfront@^3.1032.0
  - @aws-sdk/cloudfront-signer@^3.1012.0

Also fixes 4 missing destructured names in AuthService.spec.js
(getUserById, generateToken, generateRefreshToken, createSession) that
were referenced in tests but not imported from the mocked '~/models'.

* 📦 chore: install CloudFront SDK deps for PR #12193

Adds the two AWS CloudFront packages required by the rebased
CloudFront CDN strategy:
  - @aws-sdk/client-cloudfront
  - @aws-sdk/cloudfront-signer

Following the @aws-sdk/client-s3 pattern:
  - api/package.json: regular dependency (runtime resolution)
  - packages/api/package.json: peerDependency

Generated by `npm install` against the freshly rebased lock file
to avoid the merge conflicts that came from the original PR's
lock-file edits being made against an older base of dev.

* 🐛 fix: CI failures + review findings on CloudFront PR #12193

CI fixes
- Rename packages/data-provider/src/__tests__/cloudfront-config.test.ts
  → src/cloudfront-config.spec.ts. Jest's default testMatch picks up
  __tests__/ directories even inside dist/, so the compiled .d.ts shell
  was being executed as an empty test suite. Moving to .spec.ts (matching
  the rest of the package) avoids the dist/ pickup.
- Add cookieExpiry: 1800 to CloudFront crud.test makeConfig: the schema
  applies a default so CloudFrontFullConfig requires it.

Review findings addressed
- #1 (Codex + comprehensive): Normalize CloudFront domain with /\/+$/
  regex (and key with /^\/+/ regex) in buildCloudFrontUrl, matching the
  cookie code so resource policy and file URLs stay aligned even when
  the configured domain has multiple trailing slashes. Added tests.
- #2: Move DEFAULT_BASE_PATH out of s3Config into shared
  packages/api/src/storage/constants.ts. ImageService no longer imports
  S3-specific config.
- #3: getCloudFrontConfig() returns Readonly<CloudFrontFullConfig> | null
  to discourage mutation of the cached signing config.
- #4: Add cross-field refinement tests for cloudfrontConfigSchema
  (invalidateOnDelete-without-distributionId,
  imageSigning="cookies"-without-cookieDomain).
- #6: Revert unrelated MCP comment re-indentation in
  librechat.example.yaml.
- #7: Add azure_blob to the strategy list comment.

Skipped
- #5 (extractKeyFromS3Url with CloudFront URLs): existing
  deleteFileFromCloudFront tests already cover the path-equivalence
  assumption; renaming the helper is real refactor work beyond this
  PR's scope.
- #8, #9 (NIT, low confidence): leaving for author judgement.

* 🧹 chore: drop dead DEFAULT_BASE_PATH from s3Config test mock

After moving DEFAULT_BASE_PATH to ~/storage/constants, crud.ts no longer
reads it from s3Config — so the entry in the s3Config jest mock was
misleading dead config. The tests still pass because the unmocked real
constants module provides the value.

---------

Co-authored-by: Danny Avila <danny@librechat.ai>

api/package.json

@@ -36,7 +36,9 @@
   "dependencies": {
     "@anthropic-ai/vertex-sdk": "^0.14.3",
     "@aws-sdk/client-bedrock-runtime": "^3.1013.0",
+    "@aws-sdk/client-cloudfront": "^3.1042.0",
     "@aws-sdk/client-s3": "^3.980.0",
+    "@aws-sdk/cloudfront-signer": "^3.1036.0",
     "@aws-sdk/s3-request-presigner": "^3.758.0",
     "@azure/identity": "^4.13.1",
     "@azure/search-documents": "^12.0.0",