Replace deprecated audioop with NumPy and add silent join sounds

- Replace audioop module (removed in Python 3.13) with NumPy
  - Implement _apply_volume() method using NumPy for volume adjustment
  - Update RMS calculation in ducking_sound_received() to use NumPy
  - Add numpy to requirements.txt
- Add silent flag to CachedItemWrapper for join sounds
  - Join sounds now play without channel announcements
  - Regular playlist items still respect announce_current_music config
- Update CLAUDE.md to document changes

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

media/cache.py

@@ -139,11 +139,12 @@ class MusicCache(dict):
 
 
 class CachedItemWrapper:
-    def __init__(self, lib, id, type, user):
+    def __init__(self, lib, id, type, user, silent=False):
         self.lib = lib
         self.id = id
         self.user = user
         self.type = type
+        self.silent = silent  # If True, don't announce when playing (for join sounds)
         self.log = logging.getLogger("bot")
         self.version = 0
 
@@ -216,10 +217,10 @@ class CachedItemWrapper:
 
 
 # Remember!!! Get wrapper functions will automatically add items into the cache!
-def get_cached_wrapper(item, user):
+def get_cached_wrapper(item, user, silent=False):
     if item:
         var.cache[item.id] = item
-        return CachedItemWrapper(var.cache, item.id, item.type, user)
+        return CachedItemWrapper(var.cache, item.id, item.type, user, silent=silent)
     return None
 
 def get_cached_wrappers(items, user):
@@ -234,12 +235,13 @@ def get_cached_wrapper_from_scrap(**kwargs):
     item = var.cache.get_item(**kwargs)
     if 'user' not in kwargs:
         raise KeyError("Which user added this song?")
-    return CachedItemWrapper(var.cache, item.id, kwargs['type'], kwargs['user'])
+    silent = kwargs.get('silent', False)
+    return CachedItemWrapper(var.cache, item.id, kwargs['type'], kwargs['user'], silent=silent)
 
-def get_cached_wrapper_from_dict(dict_from_db, user):
+def get_cached_wrapper_from_dict(dict_from_db, user, silent=False):
     if dict_from_db:
         item = dict_to_item(dict_from_db)
-        return get_cached_wrapper(item, user)
+        return get_cached_wrapper(item, user, silent=silent)
     return None
 
 def get_cached_wrappers_from_dicts(dicts_from_db, user):
@@ -250,10 +252,10 @@ def get_cached_wrappers_from_dicts(dicts_from_db, user):
 
     return items
 
-def get_cached_wrapper_by_id(id, user):
+def get_cached_wrapper_by_id(id, user, silent=False):
     item = var.cache.get_item_by_id(id)
     if item:
-        return CachedItemWrapper(var.cache, item.id, item.type, user)
+        return CachedItemWrapper(var.cache, item.id, item.type, user, silent=silent)
 
 def get_cached_wrappers_by_tags(tags, user):
     items = var.cache.get_items_by_tags(tags)