feat: add 'state' field to mood activities for richer Discord presence

- Add 'state' field to all 139 activity entries in activities.yaml
  - Songs: state shows artist (e.g. 'by kz (livetune)')
  - Games: state shows genre (e.g. 'Rhythm Game', 'Sandbox', 'FPS')
- Update pick_activity_for_mood() to return 3-tuple (type, name, state)
- Update update_bot_presence() to pass state to discord.Activity()
- Add state validation in set_activities_for_mood() (optional string)
- Update Web UI editor: view shows state, edit form has state input
- State is fully optional — backward compatible, no breaking changes

The 'state' field appears as a secondary text line in Discord profile
popup, the richest display possible for bot accounts (full Rich Presence
with cover art/buttons is server-side restricted to OAuth applications).

bot/utils/activities.py

@@ -103,6 +103,8 @@ def set_activities_for_mood(mood_name: str, is_evil: bool, activities: list):
             raise ValueError(f"Entry {i} must have a non-empty string 'name'")
         if not isinstance(entry.get("weight", 0), int) or entry.get("weight", 0) < 1:
             raise ValueError(f"Entry {i} weight must be a positive integer")
+        if "state" in entry and entry["state"] is not None and not isinstance(entry["state"], str):
+            raise ValueError(f"Entry {i} 'state' must be a string if provided")
 
     section = "evil" if is_evil else "normal"
     data = _load_activities()
@@ -116,19 +118,19 @@ def pick_activity_for_mood(mood_name: str, is_evil: bool = False):
     """Pick a weighted-random activity for a mood.
     
     Returns:
-        tuple: (activity_type, name) e.g. ("listening", "World is Mine")
-               Returns ("listening", "Vocaloid") as fallback if mood has no entries.
+        tuple: (activity_type, name, state) e.g. ("listening", "World is Mine", "by ryo (supercell)")
+               state may be None if not defined. Fallback: ("listening", "Vocaloid", None)
     """
     activities = get_activities_for_mood(mood_name, is_evil)
 
     if not activities:
         logger.debug(f"No activities defined for {'evil/' if is_evil else ''}{mood_name}, using fallback")
-        return ("listening", "Vocaloid")
+        return ("listening", "Vocaloid", None)
 
     # Weighted random selection
     weights = [entry.get("weight", 1) for entry in activities]
     chosen = random.choices(activities, weights=weights, k=1)[0]
-    return (chosen["type"], chosen["name"])
+    return (chosen["type"], chosen["name"], chosen.get("state"))
 
 
 async def update_bot_presence(mood_name: str, is_evil: bool = False):
@@ -151,16 +153,19 @@ async def update_bot_presence(mood_name: str, is_evil: bool = False):
             logger.info("Set presence: idle (asleep)")
             return
 
-        activity_type, name = pick_activity_for_mood(mood_name, is_evil)
+        activity_type, name, state = pick_activity_for_mood(mood_name, is_evil)
 
         if activity_type == "listening":
-            activity = discord.Activity(type=discord.ActivityType.listening, name=name)
+            activity = discord.Activity(type=discord.ActivityType.listening, name=name, state=state)
             log_label = f"Listening to {name}"
         else:
-            activity = discord.Game(name=name)
+            activity = discord.Activity(type=discord.ActivityType.playing, name=name, state=state)
             log_label = f"Playing {name}"
 
-        await globals.client.change_presence(activity=activity)
+        if state:
+            log_label += f" ({state})"
+
+        await globals.client.change_presence(status=discord.Status.online, activity=activity)
         logger.info(f"Set presence: {log_label} (mood={'evil/' if is_evil else ''}{mood_name})")
 
     except Exception as e: