Fix vision pipeline: ffmpeg removal by autoremove, increase vision timeout, reduce frame count, add Discord activity awareness

- bot/Dockerfile: Add ffmpeg to reinstall line after apt-get autoremove
  (autoremove was sweeping up ffmpeg as 'no longer needed' after playwright install)
- bot/utils/image_handling.py: Increase video analysis timeout 120s→300s, 6→3 for Tenor GIFs (GTX 1660 VRAM constraint)
- bot/utils/activities.py: Add _activity_changed_at timestamp tracking,
  get_current_activity_label() and get_current_activity_fresh() with 30-min decay
- bot/utils/cat_client.py: Pass current Discord activity to Cheshire Cat pipeline
- bot/utils/llm.py: Inject current Discord activity into system prompt
- cat-plugins/*: Forward Discord activity through working_memory to personality plugins
- bot/persona/*/preamble.txt: Add Discord status usage guidelines for character prompts
- llama-swap-rocm-config.yaml: Add qwen3.5 model entry for ComfyUI prompt generation
- AGENTS.md: New project documentation file

bot/utils/activities.py

@@ -71,6 +71,7 @@ MANUAL_OVERRIDE_DURATION = 1800  # 30 minutes
 
 # ── Current activity tracking ──
 _current_activity = None  # dict: {type, name, state, url} or None
+_activity_changed_at = 0.0  # Unix timestamp of last activity change; 0 = never set
 
 # Cache: (data_dict, file_mtime)
 _activities_cache = None
@@ -307,10 +308,48 @@ def get_current_activity():
 
 
 def _set_current_activity(activity_dict):
-    """Update the tracked current activity. Thread-safe."""
-    global _current_activity
+    """Update the tracked current activity. Thread-safe.
+    
+    Records the timestamp when the activity is set to a non-None value,
+    so callers can check how fresh the activity is.
+    """
+    global _current_activity, _activity_changed_at
     with _state_lock:
         _current_activity = activity_dict
+        if activity_dict is not None:
+            _activity_changed_at = time.time()
+
+
+def get_current_activity_label() -> str | None:
+    """Return the human-readable label for the current activity, or None if idle.
+    
+    Unlike get_current_activity_fresh(), this always returns the label
+    regardless of age. Useful for the Web UI and API endpoints.
+    """
+    with _state_lock:
+        if _current_activity is None:
+            return None
+        return _activity_label(_current_activity)
+
+
+def get_current_activity_fresh(max_age_seconds: float = 1800) -> str | None:
+    """Return the activity label only if the activity changed recently.
+    
+    Args:
+        max_age_seconds: Maximum age in seconds (default 30 minutes).
+        
+    Returns:
+        Human-readable activity label (e.g. "Playing osu!") if the activity
+        was set within max_age_seconds, or None if idle or too old.
+    """
+    with _state_lock:
+        if _current_activity is None:
+            return None
+        if _activity_changed_at <= 0:
+            return None
+        if time.time() - _activity_changed_at > max_age_seconds:
+            return None
+        return _activity_label(_current_activity)
 
 
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