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-021.md

@@ -1,7 +1,7 @@
 ---
 active: true
 derived: false
-header: 'CAN-Status-Frame'
+header: 'CAN status frame'
 level: 1.21
 normative: true
 reviewed: null
@@ -10,6 +10,6 @@ links:
 asil: QM
 ---
 
-# SWE-021: CAN-Status-Frame
+# SWE-021: CAN status frame
 
-Status-Frame 0x3A0 mit 50 Hz: Byte 0 = Status (0=Released, 1=Applied, 2=Applying, 3=Releasing, 0xFF=Error), Byte 1-2 = Klemmkraft links, Byte 3-4 = Klemmkraft rechts.
+Status frame 0x3A0 at 50 Hz: byte 0 = status (0=released, 1=applied, 2=applying, 3=releasing, 0xFF=error), byte 1-2 = left clamping force, byte 3-4 = right clamping force.