0.31.0: hardening and correctness pass across mux, codec, AACS/CSS, UDF/MPLS/CLPI, recovery, drive/SCSI, labels, and I/O

Library-wide review-and-fix pass: tightened AACS keydb/handshake/variant
handling and trailing-partial-unit policy, corrected MPLS mark offset and
added UDF allocation bounds, hardened the mux/codec framing and M2TS paths,
guarded SCSI READ CAPACITY short transfers and unified error mapping, added
overflow guards on untrusted disc input, and made prefetch shutdown
deterministic. Release profile now builds with thin LTO + single codegen unit.

.github/workflows/leak-guard.yml

@@ -0,0 +1,35 @@
+name: leak-guard
+
+# Self-contained public-repo leak gate. Public CI cannot reach the private
+# tooling, so this encodes only the generic net: internal-infra references,
+# tracked CLAUDE.md/.claude paths, and AI-attribution in commit messages.
+# No project-specific reverse-engineering vocabulary lives here.
+
+on: [push, pull_request]
+
+jobs:
+  leak-guard:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v5
+        with:
+          fetch-depth: 0
+      - name: Compute commit range
+        id: range
+        run: |
+          if [ "${{ github.event_name }}" = "pull_request" ]; then
+            base="${{ github.event.pull_request.base.sha }}"
+            head="${{ github.event.pull_request.head.sha }}"
+            echo "range=$base..$head" >> "$GITHUB_OUTPUT"
+          else
+            before="${{ github.event.before }}"
+            after="${{ github.sha }}"
+            # New branch / first push: github.event.before is all-zeros.
+            if [ -z "$before" ] || [ "$before" = "0000000000000000000000000000000000000000" ]; then
+              echo "range=$after" >> "$GITHUB_OUTPUT"
+            else
+              echo "range=$before..$after" >> "$GITHUB_OUTPUT"
+            fi
+          fi
+      - name: Run leak-guard
+        run: bash ci/leak-guard.sh "${{ steps.range.outputs.range }}"