Add centralized bounty issue discovery homepage

[chico10117]

Closes #43.\n\n## Summary\n- Replaces the root homepage with a centralized issue discovery view for Pvium bounty issues.\n- Moves the existing setup/deployment homepage to /deploy.\n- Adds recent/top sorting, minimum bounty filtering, bounty summary metrics, and GitHub issue links with public metadata enrichment when available.\n- Syncs package-lock.json with the existing package.json @pvium/sdk version so npm install/build works from a clean clone.\n\n## Verification\n- npm test\n- npm run typecheck\n- npm run build\n- Local smoke check: GET / and /deploy returned 200 on localhost:3107\n\nPayout/contact wallet if needed: 0x820a7bf90d944bb26bfD9b62Ab172Fc3A0829cB9

[vercel]

@chico10117 is attempting to deploy a commit to the Bytegum Team on Vercel.

A member of the Team first needs to authorize it.

[chico10117]

Validation note: the Vercel check is currently blocked by Bytegum team deployment authorization, not by a code/build failure in this branch.

Local verification after syncing package-lock.json:

• npm run prisma:generate
• npm test
• npm run typecheck
• npm run build

Observed: unit tests passed (16/16), TypeScript passed, and Next build completed successfully. I also smoke-checked GET / and GET /deploy locally; both returned HTTP 200. The root page handles missing local DATABASE_URL with a non-crashing fallback, while production should render stored bounty data when the configured database is available.