feat: implement adapter/telegram/ with aiogram 3.x

Virtual DM chats, FSM (idle/waiting_response/settings states),
SQLite local DB for tg_users+chats, converter, keyboards, and
handlers for /start, /new, /chats, /settings, confirm callbacks.

adapter/telegram/converter.py

@@ -0,0 +1,50 @@
+# adapter/telegram/converter.py
+from __future__ import annotations
+
+from aiogram.types import Message
+
+from core.protocol import Attachment, IncomingMessage, OutgoingEvent, OutgoingMessage, OutgoingUI
+
+
+def from_message(message: Message, chat_id: str) -> IncomingMessage:
+    return IncomingMessage(
+        user_id=str(message.from_user.id),
+        chat_id=chat_id,
+        text=message.text or message.caption or "",
+        attachments=_extract_attachments(message),
+        platform="telegram",
+    )
+
+
+def _extract_attachments(message: Message) -> list[Attachment]:
+    attachments: list[Attachment] = []
+    if message.photo:
+        file = message.photo[-1]
+        attachments.append(Attachment(
+            type="image",
+            url=f"tg://file/{file.file_id}",
+            mime_type="image/jpeg",
+        ))
+    if message.document:
+        attachments.append(Attachment(
+            type="document",
+            url=f"tg://file/{message.document.file_id}",
+            mime_type=message.document.mime_type or "application/octet-stream",
+            filename=message.document.file_name,
+        ))
+    if message.voice:
+        attachments.append(Attachment(
+            type="audio",
+            url=f"tg://file/{message.voice.file_id}",
+            mime_type="audio/ogg",
+        ))
+    return attachments
+
+
+def format_outgoing(chat_name: str, event: OutgoingEvent) -> str:
+    prefix = f"[{chat_name}] "
+    if isinstance(event, OutgoingMessage):
+        return prefix + event.text
+    if isinstance(event, OutgoingUI):
+        return prefix + event.text
+    return prefix + str(event)