Classify metadata identity reconciliation buckets

[chubes4]

Summary

• Split inconsistent metadata identity rows into actionable buckets for stale metadata, branch-renamed worktrees, default-branch checkouts in feature worktrees, and manual-review cases.
• Add proposed source-of-truth and next-command guidance for each class.
• Keep automatic writes metadata-only and limited to stale identity repairs after dirty/unpushed safety checks pass.

Fixes #648.

Verification

• php tests/smoke-worktree-metadata-reconcile.php
• php -l inc/Workspace/WorkspaceMetadataReconciliation.php
• php -l tests/smoke-worktree-metadata-reconcile.php
• git diff --check -- inc/Workspace/WorkspaceMetadataReconciliation.php tests/smoke-worktree-metadata-reconcile.php

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode (openai/gpt-5.5)
• Used for: Drafted the reconciliation classification implementation and focused smoke coverage; Chris remains responsible for review and testing.