fix(profile) Handle resource-limited GitHub profile queries

[sfitzgerald-x1]

Summary

Fixes profiles that exist on GitHub but show as "No GitHub user by that name" when GitHub GraphQL rejects GitFut's full contribution query with RESOURCE_LIMITS_EXCEEDED.

Changes Introduced

• Treat non-rate-limit GraphQL execution errors as real errors instead of collapsing data.user: null into notfound.
• Preserve GitHub's real NOT_FOUND GraphQL response shape on the existing 404/notfound path.
• Keep usable partial GraphQL profile data when GitHub returns field-level errors alongside data.user.
• Add a resource-limit recovery path that fetches profile basics, then rebuilds detailed contribution data from short contribution windows when GitHub refuses the one-shot query.
• Recover real recent commits, PRs, reviews, issues, restricted contributions, active-day calendar data, and contributed-repo language data for affected profiles.
• Fetch lifetime contribution totals with typed contribution fields and recursively split if a yearly range is too expensive.
• Add regression coverage for RESOURCE_LIMITS_EXCEEDED, generic GraphQL execution errors, real NOT_FOUND responses, and partial-data responses.

Risk Assessment

• Normal successful profile scouts keep using the existing full query path.
• The detailed fallback is used only for GitHub resource-limit failures and limits concurrent fallback requests to avoid a burst of GraphQL calls.
• If a specific fallback window still fails from a transient network/resource issue after retry, that window degrades to zero rather than failing the whole scout, matching the existing best-effort lifetime behavior.
• No dependency or schema changes.

Verification Evidence

• npx vitest run tests/client.test.ts - 19 tests passed.
• npm test - 21 files / 241 tests passed.
• npx tsc --noEmit - passed.
• npm run lint - passed with existing warnings only.
• Local live check: GET /api/card/sfitzgerald-x1 now returns a detailed card with PRs, reviews, active days, contributed repo language data, and lifetime contributions instead of a false 404.
• Local live check: GET /api/card/definitely-missing-gitfut-user-xyz still returns 404 with No GitHub user by that name.

Screenshot Comparison

Production https://gitfut.com/sfitzgerald-x1	Localhost after this fix