feat(i18n): tools + landing page + doorstop generator in English

Phase 1 of full English translation:
- generate_doorstop_items.py: all 55 items (SG/SYS/SWE/SA/SWA) rewritten in English
- generate_landing_page.py: full UI labels, KPI cards, section headings in English
- traceability.py: docstring, error messages, HTML headers in English
- generate_test_report.py: report content + table headers in English
- All 55 markdown items in safety/sg/, reqs/, arch/ regenerated in English

Still to come:
- demo-epb filled Word docs (PID, plans, safety, manuals, audit artefacts)
- Code comments + test names + CI workflow step names
- README + dev-process repo templates

reqs/sys/SYS-004.md

@@ -1,7 +1,7 @@
 ---
 active: true
 derived: false
-header: 'Auto-Apply bei Motor-Aus'
+header: 'Auto-apply on engine off'
 level: 1.4
 normative: true
 reviewed: null
@@ -10,6 +10,6 @@ links:
 asil: D
 ---
 
-# SYS-004: Auto-Apply bei Motor-Aus
+# SYS-004: Auto-apply on engine off
 
-Wenn der Motor ausgeschaltet wird und das Fahrzeug stillsteht und keine Parkbremse aktiv ist, muss das System die Parkbremse spaetestens 2 s nach Erkennung Motor-Aus automatisch anlegen. Sicherheitsziel: SG-01.
+When the engine is switched off and the vehicle is at a standstill, and the parking brake is not yet engaged, the system must automatically engage the parking brake at the latest 2 s after detecting engine-off. Safety goal: SG-001.