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/swe/SWE-003.md

@@ -1,7 +1,7 @@
 ---
 active: true
 derived: false
-header: 'Schalter-Apply-Signal an Apply-Controller weiterleiten'
+header: 'Forward switch apply signal to the apply controller'
 level: 1.3
 normative: true
 reviewed: null
@@ -10,6 +10,6 @@ links:
 asil: D
 ---
 
-# SWE-003: Schalter-Apply-Signal an Apply-Controller weiterleiten
+# SWE-003: Forward switch apply signal to the apply controller
 
-Das Software-Modul Switch-Debouncer muss ein entprelltes Apply-Signal innerhalb von 50 ms an den Apply-Controller liefern.
+The Switch Debouncer software module must deliver a debounced apply signal to the apply controller within 50 ms.