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>

agent-core/brain/__init__.py

@@ -0,0 +1,22 @@
+"""
+Shared Brain for Breakpilot Agents
+
+Provides:
+- MemoryStore: Long-term memory with TTL and access tracking
+- ConversationContext: Session context with message history
+- KnowledgeGraph: Entity relationships and semantic connections
+"""
+
+from agent_core.brain.memory_store import MemoryStore, Memory
+from agent_core.brain.context_manager import ConversationContext, ContextManager
+from agent_core.brain.knowledge_graph import KnowledgeGraph, Entity, Relationship
+
+__all__ = [
+    "MemoryStore",
+    "Memory",
+    "ConversationContext",
+    "ContextManager",
+    "KnowledgeGraph",
+    "Entity",
+    "Relationship",
+]