refactor(bot): centralize runtime state; support albums + safer vision handling

- make MessageStore.put() return StoredMessage and allow collectReplyChainText() to work with StoredMessage
- move muted users + answers loading into Environment (add Answers model + GEMINI_IMAGE_MODEL)
- extract message handling into processNewMessage() and add media-group (album) caching/downloading by unique_file_id
- for Ollama: check model capabilities before sending images; use replyToMessage helper consistently
- add /geminiGenImage command stub for Gemini image generation

src/common/message-store.ts

@@ -14,7 +14,7 @@ export class MessageStore {
         return this.map;
     }
 
-    static async put(m: Message | StoredMessage) {
+    static async put(m: Message | StoredMessage): Promise<StoredMessage> {
         const msg: StoredMessage = isStoredMessage(m) ? m : {
             chatId: m.chat.id,
             id: m.message_id,
@@ -26,6 +26,7 @@ export class MessageStore {
 
         this.map.set(this.key(msg.chatId, msg.id), msg);
         await messageDao.insert(messageDao.mapStoredTo([msg]));
+        return msg;
     }
 
     static async get(chatId: number, messageId: number): Promise<StoredMessage | null> {