feat: add YAML frontmatter, bitcoin-conventions skill, path rules, and Gitea CI

- Added YAML frontmatter to all 8 polish-* skills and sweep skill
  so Claude can auto-invoke them
- New bitcoin-conventions skill with PROUX UX methodology, sats display,
  address validation, Tor preferences, Lightning patterns
- Path-specific rules for containers (security hardening) and frontend
  (Vue/glassmorphism conventions)
- Gitea Actions: nightly security review and weekly dependency audit

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

.gitea/workflows/weekly-dep-audit.yml

@@ -0,0 +1,29 @@
+name: Weekly Dependency Audit
+on:
+  schedule:
+    - cron: '13 2 * * 0'
+  workflow_dispatch:
+
+jobs:
+  audit:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Rust dependency audit
+        run: |
+          cargo install cargo-audit 2>/dev/null || true
+          echo "=== Cargo Audit ==="
+          cargo audit 2>&1 | tee cargo-audit.txt || true
+
+          echo ""
+          echo "=== Version Pinning Check ==="
+          grep -n '"\*"' Cargo.toml || echo "No wildcard versions found"
+
+      - name: Check for critical vulnerabilities
+        run: |
+          if grep -qi "RUSTSEC.*critical\|vulnerability found" cargo-audit.txt 2>/dev/null; then
+            echo "::error::Critical Rust dependency vulnerabilities found"
+            exit 1
+          fi
+          echo "No critical vulnerabilities detected"