fix(backend): remove test controllers from production module and add registration guard

[egwujiohaifesinachiperpetual-max]

Closes #1416

Description

Removes TestController and TestExceptionController from AppModule to eliminate unnecessary attack surface in production environments. Production sentiment endpoints (/sentiment/analyze and /sentiment/health) have been cleanly extracted into a dedicated SentimentController in SentimentModule.

Changes Included

• Production Module: Removed TestController and TestExceptionController from apps/backend/src/app.module.ts and deleted test controller files.
• Sentiment Feature: Added SentimentController registered in SentimentModule for production sentiment analysis routes.
• Registration Guard: Added a unit test in app.module.spec.ts asserting that no controller named test* (case-insensitive) can be registered in AppModule.
• Exception Filter Unit Tests: Added unit tests in global-exception.filter.spec.ts covering BAD_REQUEST exceptions, generic Error handling in development mode, and unknown exception objects.
• E2E & Route Verification: Updated app.e2e-spec.ts to confirm /test/* and /test-exception/* paths return 404.

Acceptance Criteria Checklist

• TestExceptionController is removed from the production module.
• TestController is removed from the production module and provably unreachable.
• Exception-filter behaviour is covered by proper unit/E2E tests instead.
• A check prevents new controllers named test* from being registered in app.module.ts.
• The deployed route list is verified to no longer expose either path.

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[Cedarich]

@egwujiohaifesinachiperpetual-max Kindly resolve conflicts

[Cedarich]

Hi @egwujiohaifesinachiperpetual-max — thanks for this contribution. CI is currently failing on this pull request, so it can't be reviewed or merged yet.

Failing check:

• backend-checks — view logs

Could you take a look and push a fix? To reproduce locally:

Check	Command
backend-checks	npm run lint --prefix apps/backend && npm run test --prefix apps/backend
data-processing-checks	pytest from apps/data-processing
Test Suite (contracts)	cargo test from apps/onchain
mobile-checks	npm run lint --prefix apps/mobile && npm test --prefix apps/mobile

A couple of things that come up often: make sure your branch is rebased on the latest main, and check the logs for a formatting or lint failure rather than a real test failure — those are the most common causes here.

If the failure looks unrelated to your change, say so in a comment and we'll investigate the workflow instead of asking you to fix it. Push a new commit and CI will re-run automatically.