Fix stale bounty cache detection

[huangse199]

Summary

• Extract bounty amounts from /bounty $... text, $... labels, and Algora bot comments.
• Keep the bounty filter useful when issue bodies omit the bounty command but Algora comments or labels contain the amount.
• Reduce the page revalidation interval from 1 hour to 5 minutes so bounty data refreshes sooner.

Verification

• ./node_modules/.bin/biome.cmd check app/page.tsx lib/github.ts package.json
• ./node_modules/.bin/tsc.cmd --noEmit --ignoreDeprecations 5.0
• git diff --check
• npm run build passed; Next reported transient GitHub fetch-cache ECONNRESET warnings after successful page generation.

/claim #10

[vercel]

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[huangse199]

Added one more follow-up fix on this PR branch to make bounty amount detection less brittle.

What changed:

• recognizes formats like $300 bounty
• recognizes formats like bounty ... $300
• still supports /bounty $300
• allows nullable label names from the GitHub API
• checks title + body together, then labels, then comments, and keeps the highest detected amount

Validation:

• biome check lib/github.ts app/page.tsx passed
• tsc --noEmit passed
• next build compiled and type-checked successfully, but static generation did not complete because the build hit GitHub API/network failures (ECONNRESET / rate-limit style fetch failures) while fetching live issue data.