…1763670247049

Add Claude Code GitHub Workflow

- Fix #1: Handle missing remote branches in impl-generate.yml
  - Check if branch exists before checkout to avoid 'not a commit' errors
  - Fall back to creating fresh branch from main if remote doesn't exist

- Fix #2: Clean up duplicate labels on failure
  - Remove both 'generate:X' and 'impl:X:pending' when marking as failed
  - Prevents label accumulation (e.g., both pending and failed)

- Fix #3: Auto-close issues when done + failed = 9
  - Previously only closed when all 9 were 'done'
  - Now closes when total (done + failed) reaches 9
  - Shows which libraries failed in closing comment

- Fix #4: Track generation failures and auto-mark as failed
  - Count previous failed runs for same spec/library
  - After 3 failures, mark as 'impl:X:failed' automatically
  - Posts failure comment explaining the library may not support this plot type

…1308)

## Summary

Fixes several workflow issues discovered during batch processing of
spec-ready issues.

### Fix #1: Branch-Not-Found Errors
**Problem:** `fatal: 'origin/implementation/{spec}/{library}' is not a
commit` errors when workflow tries to checkout a non-existent remote
branch.

**Solution:** Check if remote branch exists before checkout, fall back
to creating fresh branch from main.

### Fix #2: Duplicate Labels
**Problem:** Issues accumulate both `impl:X:pending` and `impl:X:failed`
labels when generation fails.

**Solution:** Failure handler removes both `generate:X` and
`impl:X:pending` when marking as failed.

### Fix #3: Auto-Close with Failures
**Problem:** Issues with 8 done + 1 failed stay OPEN because auto-close
only triggers on 9 done.

**Solution:** Close when `done + failed = 9`, with appropriate summary
(shows which libraries failed).

### Fix #4: Generation Failure Tracking
**Problem:** When `impl-generate` fails (no plot.png), no PR is created
→ no review → no repair → library stays `pending` forever.

**Solution:** Track generation failures and mark as `impl:X:failed`
after 3 consecutive failures. Posts comment explaining the library may
not support this plot type.

## Files Changed
- `.github/workflows/impl-generate.yml` - Fixes #1, #2, #4
- `.github/workflows/impl-merge.yml` - Fix #3

## Testing
- YAML syntax validated
- Logic reviewed against observed failure patterns

Critical fixes:
- Fix TypeError: flatten tag dict to list for repository call (#6)
  Changed search_by_tags to receive list[str] instead of dict[str, list[str]]
  Repository expects flat list of tag values, not nested dict

- Add missing dataprep and styling parameters (#1, #7)
  Added to search_specs_by_tags function signature and docstring
  These categories were documented but not implemented

- Add filter logic for dataprep and styling (#2)
  Implemented filtering checks similar to other impl-level tags
  Ensures new parameters actually filter results

- Update condition to include dataprep and styling (#3)
  Modified impl-level filtering condition on line 117
  Now checks all 6 impl-level tag categories

Improvements:
- Add database error handling with helpful messages (#8)
  Check is_db_configured() before all database operations
  Provides clear error message if DATABASE_URL not set

- Update test mocks to match fixed interface (#5)
  Tests now verify flattened tag list instead of dict
  Added new test for dataprep/styling filter parameters
  Mock is_db_configured to return True in test fixture

Verification:
- All 16 unit tests passing
- Ruff linting and formatting applied
- No routing conflicts (#4 verified - no /mcp routes in routers)

Related: PR #4132, Issue #4129