fix: zero fallback repo stats (#1245)

[mittalsonal]

Description\n- replace the landing page's hardcoded non-zero fallback repo stats with zero-safe values\n- prevent invented GitHub stars, forks, issues, and contributor counts from appearing during API failures\n- keep the change scoped to etchRepoStats() in src/app/page.tsx\n\n## Related Issue\n- Closes #1245\n\n## Checklist\n- [x] one-file fix\n- [x] git diff --check passes\n- [x] behavior now falls back to zero-safe stats instead of fabricated numbers\n\n## Pillar\n- Open Source\n

[vercel]

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[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

[mittalsonal]

Kind request for GSSoC labels when reviewed: gssoc:approved, one level:* label, and ype:bug if it fits the repo’s scoring rubric. Thanks!

[mittalsonal]

Verification completed locally:

• git diff --check

This PR intentionally keeps the fix small and limited to the landing-page repo stats fallback path in src/app/page.tsx.