Remove intent router from chat pipeline; raise OLLAMA_NUM_CTX to 16384

The intent classifier (Phase 21) is removed from the main chat generation
path. The main model now handles all tool routing natively via Ollama's
structured tool-calling API, eliminating misidentification issues caused
by the small intent model.

Changes:
- generation_task.py: remove classify_intent call, intent_task, _WRITE_TOOLS,
  _TOOL_ACTIONS, _INTENT_TRIGGER_WORDS, _should_skip_intent(), and the entire
  round-0 intent-first + write-tool confirmation block (~315 lines removed)
- research_topic tool calls are now handled inline in the streaming loop:
  runs run_research_pipeline, streams synthesis to buf, then breaks the round
  loop (research is still the full response, no model follow-up)
- config.py: raise OLLAMA_NUM_CTX default from 8192 to 16384

The quick-capture dedicated classifier (classify_capture_intent) is unchanged.

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

src/fabledassistant/config.py

@@ -28,8 +28,7 @@ class Config:
     # Falls back to OLLAMA_MODEL if not set. Can also be overridden per-user via settings.
     OLLAMA_INTENT_MODEL: str = os.environ.get("OLLAMA_INTENT_MODEL", "qwen2.5:7b")
     # KV cache context window for generation. Lower = less VRAM, less throughput impact.
-    # 8192 is sufficient for most conversations; raise if you paste large documents.
-    OLLAMA_NUM_CTX: int = int(os.environ.get("OLLAMA_NUM_CTX", "8192"))
+    OLLAMA_NUM_CTX: int = int(os.environ.get("OLLAMA_NUM_CTX", "16384"))
     SECRET_KEY: str = _read_secret("SECRET_KEY", "SECRET_KEY_FILE", "dev-secret-change-me")
     SECURE_COOKIES: bool = os.environ.get("SECURE_COOKIES", "").lower() in ("1", "true", "yes")
     LOG_LEVEL: str = os.environ.get("LOG_LEVEL", "INFO")