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-001.md

@@ -1,7 +1,7 @@
 ---
 active: true
 derived: false
-header: 'Halten der Parkbremse im Stillstand'
+header: 'Holding the parking brake at standstill'
 level: 1.1
 normative: true
 reviewed: null
@@ -10,8 +10,8 @@ links:
 asil: D
 ---
 
-# SYS-001: Halten der Parkbremse im Stillstand
+# SYS-001: Holding the parking brake at standstill
 
-Wenn die Parkbremse aktiviert ist und das Fahrzeug stillsteht, muss das EPB-System die mechanische Klemmkraft an beiden hinteren Bremssaetteln aufrecht erhalten, bis ein Loesen ausdruecklich angefordert wird. Sicherheitsziel: SG-01.
+When the parking brake is engaged and the vehicle is at a standstill, the EPB system must maintain the mechanical clamping force on both rear callipers until a release is explicitly requested. Safety goal: SG-001.
 
-**Verifikation:** SiL-Test mit Auf-/Ab-Hangelung, Klemmkraftmessung.
+**Verification:** SiL test with up/down grade scenarios, clamping force measurement.