Batch dirty path classification

[chubes4]

Summary

• Batch dirty-path comparison against the default ref with one ls-tree and one diff --name-only call per inspected path set.
• Preserve existing per-path classifier as fallback when batched probes fail or time out.
• Keep existing buckets and generated/source-like classification unchanged.

Closes #377.

Testing

• php -l inc/Workspace/Workspace.php && php -l tests/smoke-worktree-metadata-reconcile.php && git diff --check
• php tests/smoke-worktree-metadata-reconcile.php
• php tests/smoke-worktree-cleanup-cli.php
• php tests/smoke-worktree-cleanup-chunks.php

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode (GPT-5.5)
• Used for: Drafted the batched dirty path classifier, smoke coverage, and verification commands for Chris to review.