fix(diff-filter): ignore Anchor generated directory

[sato820]

Summary

• Ignore Anchor's generated .anchor/ directory in diff-filter path classification.
• Add classifyPath coverage for contracts/solana/.anchor/test-ledger/genesis.bin.

Fixes #67

Tests

• pnpm --filter @ghbounty/diff-filter test
• pnpm --filter @ghbounty/diff-filter typecheck

[vercel]

@sato820 is attempting to deploy a commit to the weareghbounty-6269's projects Team on Vercel.

A member of the Team first needs to authorize it.

[sato820]

Bounty submission note for #67:

The PR is ready and the requested checks passed locally:

• pnpm --filter @ghbounty/diff-filter test
• pnpm --filter @ghbounty/diff-filter typecheck

I also configured the GH Bounty developer profile so MCP whoami now returns github_handle: sato820 and the connected Solana wallet. When I try to submit this PR through submissions.create for bounty d232f106-c1aa-4118-9db7-c139cefccce1, the server now gets past profile/delegation checks but returns:

InternalError: GAS_STATION_PUBKEY not configured.

So the MCP/on-chain submission path appears blocked by server configuration rather than the PR itself. Happy to retry the official submission flow once that is configured, or follow any manual workaround you prefer.