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

arch/sys/SA-005.md

@@ -1,7 +1,7 @@
 ---
 active: true
 derived: false
-header: 'CAN-Bus'
+header: 'CAN bus'
 level: 1.5
 normative: true
 reviewed: null
@@ -11,16 +11,17 @@ links:
 asil: QM
 ---
 
-# SA-005: CAN-Bus
+# SA-005: CAN bus
 
-## Verantwortung
+## Responsibility
 
-Kommunikations-Backbone fuer Eingangsdaten (Bremspedal, Gang, Tuer, Gurt),
-Ausgabe (Status-Frame an Display) und Diagnose (UDS auf Tester-Adresse).
+Communication backbone for input data (brake pedal, gear, door,
+belt), output (status frame to the display) and diagnostics (UDS
+on the tester address).
 
-## Schnittstellen
+## Interfaces
 
-- Baudrate: 500 kbit/s, CAN 2.0B
-- Empfangene Frames: 0x100 (Bremspedal), 0x110 (Gang), 0x120 (Door/Belt),
-  0x712 (UDS-Request)
-- Gesendete Frames: 0x3A0 (Status 50 Hz), 0x71A (UDS-Response)
+- Baud rate: 500 kbit/s, CAN 2.0B
+- Received frames: 0x100 (brake pedal), 0x110 (gear),
+  0x120 (door/belt), 0x712 (UDS request)
+- Sent frames: 0x3A0 (status 50 Hz), 0x71A (UDS response)