feat(ci): add CLAUDE.md drift detection via centralized reusable (#93)

Detects when code changes may have made CLAUDE.md stale. Two-phase:
shell pre-filter (zero LLM cost) → Haiku semantic check (only when
needed). Posts a structured PR comment if drift is found.

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: nsportsman

.github/workflows/claude-md-drift.yml

@@ -0,0 +1,20 @@
+name: CLAUDE.md Drift Detection
+
+on:
+  pull_request:
+    types: [opened, synchronize, ready_for_review]
+
+concurrency:
+  group: claude-drift-${{ github.event.pull_request.number }}
+  cancel-in-progress: true
+
+jobs:
+  drift-check:
+    uses: praetorian-inc/public-workflows/.github/workflows/claude-md-drift.yml@87c0808aa16862a7ffef0cd94c516a02eb48242b  # v2.3.0
+    timeout-minutes: 15
+    permissions:
+      contents: read
+      pull-requests: write
+    secrets:
+      ANTHROPIC_API_KEY: ${{ secrets.ANTHROPIC_API_KEY }}
+