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-009.md

@@ -1,7 +1,7 @@
 ---
 active: true
 derived: false
-header: 'UDS-Diagnose'
+header: 'UDS diagnostics'
 level: 1.9
 normative: true
 reviewed: null
@@ -9,6 +9,6 @@ links: []
 asil: QM
 ---
 
-# SYS-009: UDS-Diagnose
+# SYS-009: UDS diagnostics
 
-Das System muss UDS-Diagnose nach ISO 14229 bereitstellen: ReadDTC (0x19), ReadDataByIdentifier (0x22), RoutineControl (0x31), ECUReset (0x11). Tester-Adresse 0x712, Antwort-Adresse 0x71A.
+The system must provide UDS diagnostics per ISO 14229: ReadDTC (0x19), ReadDataByIdentifier (0x22), RoutineControl (0x31), ECUReset (0x11). Tester address 0x712, response address 0x71A.