fix(cron): Session-Takeover-Workaround, mobil-Dashboard, Import-Fix standalone

- feat(isolation): Cron-Wrapper (subprocess, /workspace/cron_tasks)
- fix(dashboard): mobil-optimierte Karten statt Tabelle
- fix(imports): sys.path + venv auto-activation
- chore: Lasse flüchtiges /tmp hinter mir

Closes-Bug: Session-Takeover bei isolated Cron
Engramme-bestaetigt: Standalone-Import-OK, Wrapper-getestet

src/__init__.py

@@ -1,8 +1,14 @@
 """Second Brain - Gedächtnissystem für OpenClaw."""
 
-from .engram import Engram, Grounding, Correctness, ReviewEntry
-from .store import EngramStore
-from .retriever import Retriever
+try:
+    from .engram import Engram, Grounding, Correctness, ReviewEntry
+    from .store import EngramStore
+    from .retriever import Retriever
+except ImportError:
+    # Fallback: ChromaDB optional, SQLite-core funktioniert immer
+    from .engram import Engram, Grounding, Correctness, ReviewEntry
+    from .store import EngramStore
+    Retriever = None
 
 __version__ = "0.1.0"
 __all__ = ["Engram", "Grounding", "Correctness", "ReviewEntry", "EngramStore", "Retriever"]