fix(web): reject non-string connected repo coordinates

[dirtybits]

Summary

• reject non-string GitHub owner and repository coordinates before regex validation can coerce them
• cover numeric, object, and array coordinate inputs alongside the existing branch-input guard

Test plan

• npm test --workspace @agentvouch/web -- __tests__/lib/mirror-connectedRepos.test.ts --maxWorkers=1 --no-fileParallelism
• npm run check — format, lint, typecheck, and all 1,394 tests passed; the final webpack production build compiled successfully but failed only during /sitemap.xml prerender because this cron worktree has no DATABASE_URL in web/.env.local
• git diff --check

Not verified

• A complete production build and any database-backed runtime flow were not verified because this worktree lacks the required DATABASE_URL.