feat: add batch fix & implement pipeline script

[zazabap]

Summary

New scripts/pipeline_batch.py — orchestrator that triages, fixes, implements, and combines batches of ⚠️ rule issues into a single PR.

4 Stages

1. Triage — classifies issues as pass/fixable/broken/blocked using keywords from Reduction rule issues tiered implementation priority #770
2. Fix — spawns Claude agents to fix mechanical issues (edits issue bodies only, no comments)
3. Implement — parallel worktree agents (up to 6 concurrent) following add-rule skill
4. Finalize — cherry-picks into one branch, make check, creates single PR

Usage

make run-batch ISSUES="238 381 166 277 363 459 523 472"
make run-batch ISSUES="166 385" JOBS=4
python3 scripts/pipeline_batch.py fix-and-implement --dry-run 277 523  # triage only

Supports resume from any stage via --from-report.

Test plan

• python3 scripts/pipeline_batch.py --help shows all subcommands
• Dry-run on broken issues ([Rule] DIRECTED TWO-COMMODITY INTEGRAL FLOW to UNDIRECTED TWO-COMMODITY INTEGRAL FLOW #277, [Rule] CLIQUE to PARTIALLY ORDERED KNAPSACK #523) correctly classifies and skips them
• Full run on fixable issues produces a combined PR

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.87%. Comparing base (006d468) to head (c050b2d).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #871   +/-   ##
=======================================
  Coverage   97.87%   97.87%           
=======================================
  Files         631      631           
  Lines       69046    69046           
=======================================
  Hits        67577    67577           
  Misses       1469     1469           

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