fix: resolve auth routing redirects and repair e2e test suite

[ArshVermaGit]

Description

This PR resolves the critical Authentication / Routing bug where unauthenticated users were incorrectly redirected to /auth/signin instead of the root / when attempting to access protected dashboard routes. Additionally, it addresses false-positive test failures by syncing the AppNavbar rendering behavior with Playwright expectations.

Resolved Issue

Resolves #1543

Changes Made

• Dashboard Guard Remediation: Replaced the default next-auth redirect behavior in src/app/dashboard/layout.tsx with an explicit onUnauthenticated() handler that pushes the router to /.
• Public Profile Navigation Link: Modified src/components/AppNavbar.tsx to hide the "Sign in with GitHub" link when the user is unauthenticated and viewing a public profile page (/u/*), resolving the toHaveCount(0) expectation failure.
• Server Component Stabilization: Removed the invalid { ssr: false } flag from dynamic component imports in src/app/dashboard/page.tsx that previously broke Next.js 15 builds and caused subsequent server crash loops.

Impact

• End-to-End Tests: npm run test:e2e now completes with 16 passed and 0 failed.
• Authentication Flow: The application now seamlessly routes unauthenticated attempts on protected pages back to the landing page without surfacing the standalone /auth/signin page directly.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

[vercel]

@ArshVermaGit is attempting to deploy a commit to the PRIYANSHU DOSHI's projects Team on Vercel.

A member of the Team first needs to authorize it.

[github-actions]

GSSoC Label Checklist 🏷️

@Priyanshu-byte-coder — please apply the appropriate labels before merging:

Difficulty (pick one):

• level:beginner — 20 pts
• level:intermediate — 35 pts
• level:advanced — 55 pts
• level:critical — 80 pts

Quality (optional):

• quality:clean — ×1.2 multiplier
• quality:exceptional — ×1.5 multiplier

Validation (required to score):

• gssoc:approved — counts for points
• gssoc:invalid / gssoc:spam / gssoc:ai-slop — does not score

Type labels (type:*) are auto-detected from files and title. Review and adjust if needed.
Points formula: (difficulty × quality_multiplier) + type_bonus

[ArshVermaGit]

Hi @Priyanshu-byte-coder ! Issue #1543 has been resolved. Please review the PR and merge it under GSSoC. Thanks!

[Priyanshu-byte-coder]

Please remove the debug files fix.js and fix2.js from this PR before merging. These are development artifacts and should not be committed to the repository.

[ArshVermaGit]

Please remove the debug files fix.js and fix2.js from this PR before merging. These are development artifacts and should not be committed to the repository.

fixed it please review