feat(iace): GT-Bremse coverage — 59 expert measures + 7 hazard patterns

Systematic gap analysis of the Bremse ground-truth file (60 entries,
100 unique expert measures) revealed only ~5% library coverage. This
commit closes the documented gaps with concrete, norm-anchored
mitigations.

Library additions (M481-M539, 59 entries):
- M481-M482  Low-voltage isolation (>= 2,0 / 2x1,0 / 1,0 MOhm +
             IP2X/IPXXB per EN 60204-1 Ziff. 6.2/8.2.3) — primary
             trigger of this work
- M483-M485  Pneumatic safety (component pressure rating, hose
             retention, depressurization per EN ISO 4414)
- M486-M490  Robot-cell access (tool-secured fence, dual-channel
             door monitor, intentional restart, anti-trap inside
             opening, HMI sight line per ISO 10218-2)
- M491-M493  Teach mode (key/password mode selector, safe reduced
             speed <= 250 mm/s, hold-to-run with 3-stage enabler
             per ISO 10218-1)
- M494-M500  Geometry constants (Safe Limited Position, reach-over
             250 mm @ 2250 mm fence, conveyor opening >= 850 mm,
             25 mm finger gap, band speed <= 100 mm/s per
             EN ISO 13857 / EN 619)
- M501-M507  Enclosure load rating, gripper fail-safe, centring
             gripper stop on door, MWF nozzle integration, floor
             load capacity per DIN 1055-3
- M508-M517  Electrical cabling + PE protection (environment-rated,
             drag chain, strain relief, 10 mm² Cu PE, dual PE,
             monitoring, continuity check, class-II equipment,
             SELV/PELV per EN 60204-1)
- M518-M522  RCD, cable cross-section, overcurrent in each active
             conductor, IP22 water ingress, lockable main switch
- M523-M539  Teach-locked door, WZM door interlock, dual-channel
             door switch, machining-doors-closed for aerosol
             retention, post-NOTHALT release, >25 kg lifting aid
             (DGUV 208-016), 95-120 cm control height, ergonomic
             conveyor height, SDS/PSA reference, BA instructions
             for depressurization/clamp release/max weight/pinch
             warning/slip warning/dead-state cleaning

New hazard patterns (HP1710-HP1717):
floor overload, gripper failure throw, compressed-air injury in
machining cell, manual handling load + awkward posture, MWF skin
contact, live-cabinet cleaning short, pneumatic stored-energy.

Existing patterns rewired to the new measures: HP1600, HP1602-1606,
HP1610-1612, HP1620-1622, HP1630/1631/1633, HP1640/1641, HP1660/1661,
HP1675, HP1685, HP1688, HP1689, HP1698-1704.

Tooling:
- scripts/gt_measure_gap_analysis.py: 4-signal fuzzy matcher
  (Jaccard, token recall, substring containment, norm-reference
  overlap). Outputs markdown + JSON.
- gt_coverage_test.go: 23 expert-validated (GT-Nr, pattern, measure)
  triples + a norm-reference presence test for every new expert
  measure (no generic 'do X safely' entries allowed).
- .gitea/workflows/ci.yaml: new iace-gt-coverage job enforces
  MIN_COVERAGE_PCT (70%) on Strong+Weak GT coverage; never lower
  without explicit decision.

Coverage shift: 5% Strong -> 30% Strong, 0% -> 72% Strong+Weak.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.gitea/workflows/ci.yaml

@@ -314,6 +314,40 @@ jobs:
           go test -v -coverprofile=coverage.out ./...
           go tool cover -func=coverage.out | tail -1
 
+  iace-gt-coverage:
+    runs-on: docker
+    container: python:3.12-slim
+    needs: detect-changes
+    if: needs.detect-changes.outputs.sdk == 'true'
+    env:
+      # Lower bound on Strong+Weak GT-Bremse coverage. Raise this number when
+      # coverage improves; never lower it without an explicit decision.
+      MIN_COVERAGE_PCT: "70"
+    steps:
+      - name: Checkout
+        run: |
+          apt-get update -qq && apt-get install -y -qq git > /dev/null 2>&1
+          git clone --depth 1 --branch ${GITHUB_REF_NAME} ${GITHUB_SERVER_URL}/${GITHUB_REPOSITORY}.git .
+      - name: GT-Bremse measure-coverage report
+        run: |
+          python3 scripts/gt_measure_gap_analysis.py --json /tmp/gt_gap_report.json > /tmp/gt_gap_report.md
+          echo "--- summary ---"
+          head -8 /tmp/gt_gap_report.md
+      - name: Enforce coverage threshold
+        run: |
+          python3 - <<'PY'
+          import json, os, sys
+          d = json.load(open('/tmp/gt_gap_report.json'))
+          total = d['total']
+          covered = d['ok_count'] + d['weak_count']
+          pct = covered * 100 / total if total else 0.0
+          threshold = float(os.environ['MIN_COVERAGE_PCT'])
+          print(f"GT coverage (strong+weak): {covered}/{total} = {pct:.1f}% (threshold {threshold}%)")
+          if pct < threshold:
+              print(f"::error::GT-Bremse coverage regression — {pct:.1f}% < {threshold}%")
+              sys.exit(1)
+          PY
+
   test-python-backend:
     runs-on: docker
     container: python:3.12-slim