fix: Restore all files lost during destructive rebase

A previous `git pull --rebase origin main` dropped 177 local commits,
losing 3400+ files across admin-v2, backend, studio-v2, website,
klausur-service, and many other services. The partial restore attempt
(660295e2) only recovered some files.

This commit restores all missing files from pre-rebase ref 98933f5e
while preserving post-rebase additions (night-scheduler, night-mode UI,
NightModeWidget dashboard integration).

Restored features include:
- AI Module Sidebar (FAB), OCR Labeling, OCR Compare
- GPU Dashboard, RAG Pipeline, Magic Help
- Klausur-Korrektur (8 files), Abitur-Archiv (5+ files)
- Companion, Zeugnisse-Crawler, Screen Flow
- Full backend, studio-v2, website, klausur-service
- All compliance SDKs, agent-core, voice-service
- CI/CD configs, documentation, scripts

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/data/units/update_test_caa8de53.json

@@ -0,0 +1,58 @@
+{
+  "unit_id": "update_test_caa8de53",
+  "template": "flight_path",
+  "version": "1.0.0",
+  "locale": [
+    "de-DE"
+  ],
+  "grade_band": [
+    "5",
+    "6",
+    "7"
+  ],
+  "duration_minutes": 10,
+  "difficulty": "base",
+  "subject": "Updated Subject",
+  "topic": "New Topic",
+  "learning_objectives": [],
+  "stops": [
+    {
+      "stop_id": "stop_1",
+      "order": 0,
+      "label": {
+        "de-DE": "Stop 1"
+      },
+      "narration": {
+        "de-DE": "Original"
+      },
+      "interaction": {
+        "type": "toggle_switch",
+        "params": {}
+      }
+    }
+  ],
+  "precheck": {
+    "question_set_id": "update_test_caa8de53_precheck",
+    "required": true,
+    "time_limit_seconds": 120
+  },
+  "postcheck": {
+    "question_set_id": "update_test_caa8de53_postcheck",
+    "required": true,
+    "time_limit_seconds": 180
+  },
+  "teacher_controls": {
+    "allow_skip": true,
+    "allow_replay": true,
+    "max_time_per_stop_sec": 90,
+    "show_hints": true,
+    "require_precheck": true,
+    "require_postcheck": true
+  },
+  "assets": {},
+  "metadata": {
+    "author": "Unknown",
+    "created": "2026-01-13T13:36:15.491371",
+    "curriculum_reference": ""
+  }
+}