feat: Langzeit-Erinnerungen (#3b) und WebSocket-Streaming-Chat (#4, erster Increment)

#3b Langzeit-Erinnerungen:
- Store: memories-Tabelle + add/get/delete_memory (pro Nutzer)
- API: GET/POST/DELETE /api/me/memories
- chat.py injiziert Nutzer-Erinnerungen als System-Kontext ins LLM (sessionunabhaengig)
- ?debug zeigt memories_len

#4 Echtzeit (erster Increment):
- WS /ws/chat: dauerhafter Kanal, Event-Folge ack -> semantic -> audio (binaer) -> done
- Auth (Token-Query), Session-Gedaechtnis und Erinnerungen wie bei POST /api/chat
- Fehler als error-Event (422/403/502)

- Tests: 38 gruen (Erinnerungs-CRUD/Injektion, WebSocket-Streaming/Auth)
- Doku aktualisiert (README, BEDIENUNGSANLEITUNG, Architektur)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/test_ws.py

@@ -0,0 +1,68 @@
+import pytest
+from fastapi.testclient import TestClient
+from starlette.websockets import WebSocketDisconnect
+
+import app.dependencies as deps
+from app.main import app
+from app.config import settings
+
+client = TestClient(app)
+
+
+def _install_stubs(monkeypatch, captured):
+    class MemLLM:
+        async def complete(self, text, history=None, session_id=None):
+            captured["history"] = list(history or [])
+            return f"Echo: {text}"
+
+    class StubTTS:
+        async def synthesize(self, text, voice=None, audio_format="pcm"):
+            return b"WSAUDIO"
+
+    monkeypatch.setitem(deps.LLM_REGISTRY, "mem", lambda s: MemLLM())
+    monkeypatch.setitem(deps.TTS_REGISTRY, "stub", lambda s: StubTTS())
+    return {"llm_provider": "mem", "tts_provider": "stub", "output_endpoint": "loopback"}
+
+
+def _drain_turn(ws):
+    assert ws.receive_json()["type"] == "ack"
+    sem = ws.receive_json()
+    assert ws.receive_bytes() == b"WSAUDIO"
+    assert ws.receive_json()["type"] == "done"
+    return sem
+
+
+def test_ws_streams_events_and_remembers(monkeypatch):
+    captured = {}
+    base = _install_stubs(monkeypatch, captured)
+
+    with client.websocket_connect("/ws/chat?session_id=wsconv") as ws:
+        ws.send_json({"text": "Hallo", **base})
+        sem1 = _drain_turn(ws)
+        assert sem1["type"] == "semantic" and sem1["text"] == "Echo: Hallo"
+
+        ws.send_json({"text": "Weiter", **base})
+        _drain_turn(ws)
+
+    # Zweiter Turn hat den Verlauf des ersten erhalten.
+    assert captured["history"] == [
+        {"role": "user", "content": "Hallo"},
+        {"role": "assistant", "content": "Echo: Hallo"},
+    ]
+
+
+def test_ws_unknown_provider_sends_error_event(monkeypatch):
+    captured = {}
+    _install_stubs(monkeypatch, captured)
+    with client.websocket_connect("/ws/chat") as ws:
+        ws.send_json({"text": "x", "llm_provider": "gibtsnicht"})
+        err = ws.receive_json()
+        assert err["type"] == "error" and err["status"] == 422
+
+
+def test_ws_requires_token_when_auth_enabled(monkeypatch):
+    monkeypatch.setattr(settings, "auth_enabled", True)
+    monkeypatch.setattr(settings, "admin_api_key", "k")
+    with pytest.raises(WebSocketDisconnect):
+        with client.websocket_connect("/ws/chat"):
+            pass