feat(auth): add JWT token revocation with Redis blocklist

[antharya05]

Summary

Implements secure JWT session invalidation using Redis blocklisting.

Previously, JWTs remained valid until expiration even after logout, meaning a stolen token could continue accessing protected APIs after a user logged out. This PR introduces server-side token revocation support so tokens are immediately invalidated after logout.

Closes #306

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Type of Change

• New feature
• Security
• Tests only

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What Changed

• Added protected DELETE /auth/logout endpoint for secure token revocation
• Added Redis-backed JWT blocklist support with automatic TTL cleanup
• Added shared JWT utility helpers in src/utils/jwt.ts
• Extended global authenticate middleware to reject revoked tokens before jwtVerify()
• Added logout/session revocation tests in src/__tests__/logout.test.ts
• Preserved compatibility with existing OAuth/auth flows during rebase conflict resolution
• Added hashed token signature storage instead of storing raw JWTs directly

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How to Test

1. Start Docker services and backend:

docker compose up -d
cd apps/backend
npx tsx src/server.ts

2. Generate a JWT token:

$response = Invoke-RestMethod `
  -Method POST `
  -Uri http://localhost:3000/auth/dev-login `
  -ContentType "application/json" `
  -Body "{}"

$token = $response.token

3. Verify authenticated access works:

Invoke-RestMethod `
  -Uri http://localhost:3000/api/profiles/me `
  -Headers @{ Authorization = "Bearer $token" }

4. Logout and revoke the token:

Invoke-RestMethod `
  -Method DELETE `
  -Uri http://localhost:3000/auth/logout `
  -Headers @{ Authorization = "Bearer $token" }

5. Retry the same request using the same token:

Invoke-RestMethod `
  -Uri http://localhost:3000/api/profiles/me `
  -Headers @{ Authorization = "Bearer $token" }

Expected result:

• Request fails with 401 Unauthorized

6. Run logout tests:

cd apps/backend
pnpm vitest run src/__tests__/logout.test.ts

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Checklist

• My code follows the project's coding style (pnpm -r run lint passes).
• TypeScript compiles without errors (pnpm -r run typecheck).
• I have added or updated tests for the changes I made.
• All tests pass locally (pnpm -r run test).
• I have updated documentation where necessary.
• No new console.log or debug statements left in the code.
• Breaking changes are documented in this PR description.

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Screenshots / Recordings

Attached:

• Successful authenticated request before logout
• Successful logout response
• Revoked token returning 401 Unauthorized
• Passing logout test suite

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Additional Context

• Redis blocklist entries use TTL equal to remaining JWT lifetime, so entries self-expire automatically.
• Redis stores hashed token signatures instead of raw JWTs for improved security.
• Redis failures intentionally use a fail-open strategy to avoid taking down all authenticated requests during Redis outages.
• Existing unrelated failing tests in event.test.ts were already present in the repository and are unrelated to this implementation.

[antharya05]

hey @Harxhit , @ShantKhatri , please look into this PR, thank you.