chore: remove disabled workflows, keep only build-iso

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

.gitea/workflows/nightly-security.yml

@@ -1,45 +0,0 @@
-name: Nightly Security Review
-on:
-  schedule:
-    - cron: '47 1 * * *'
-  workflow_dispatch:
-
-jobs:
-  security-review:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-
-      - name: Install Claude Code
-        run: npm install -g @anthropic-ai/claude-code
-
-      - name: Run security review on recent changes
-        env:
-          ANTHROPIC_API_KEY: ${{ secrets.ANTHROPIC_API_KEY }}
-        run: |
-          CHANGED=$(git diff --name-only HEAD~1..HEAD 2>/dev/null || echo "")
-          if [ -z "$CHANGED" ]; then
-            echo "No recent changes to review"
-            exit 0
-          fi
-
-          claude --print "Run a security review focused on these recently changed files:
-          $CHANGED
-
-          Check for:
-          - Constant-time comparison violations in crypto code
-          - Private key material in logs or error messages
-          - Floating-point Bitcoin amounts (must be integer sats)
-          - eval() or unsafe blocks without SAFETY comments
-          - Hardcoded credentials or secrets
-          - Missing input validation at API boundaries
-
-          Output a structured report with severity levels.
-          If any CRITICAL issues found, exit with code 1." > security-report.txt 2>&1
-
-          cat security-report.txt
-
-          if grep -qi "critical" security-report.txt; then
-            echo "::error::Critical security issues found — review security-report.txt"
-            exit 1
-          fi

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

@@ -1,29 +0,0 @@
-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"