feat: add Telegram file attachment support (inbound + outbound)

Inbound:
- tg-ingest detects document/photo/audio/video/voice attachments
- Downloads files via Telegram Bot API (getFile + download)
- Inlines small text files (<50KB) directly in the prompt
- Stores binary/large files to S3 (attachments/{chat_id}/{update_id}/{filename})
- agent-runner appends file context to the AgentCore prompt

Outbound:
- New send_file tool for the agent to send documents back to users
- TelegramAdapter.send_document uses multipart/form-data POST
- CDK grants tg-ingest S3 write access and passes bucket name env var

agentclaw/app/agent_claw_main/channels/telegram.py

@@ -63,6 +63,43 @@ class TelegramAdapter:
             import traceback
             print(f'[telegram] send_typing failed: {e}\n{traceback.format_exc()}')
 
+    def send_document(self, file_bytes: bytes, filename: str, caption: str = '') -> str:
+        """Send a file as a Telegram document using multipart/form-data. Returns message_id."""
+        import io
+        token = self._get_token()
+        url = f'https://api.telegram.org/bot{token}/sendDocument'
+
+        boundary = '----AgentClawBoundary'
+        body = io.BytesIO()
+
+        def add_field(name: str, value: str):
+            body.write(f'--{boundary}\r\n'.encode())
+            body.write(f'Content-Disposition: form-data; name="{name}"\r\n\r\n'.encode())
+            body.write(f'{value}\r\n'.encode())
+
+        def add_file(name: str, fname: str, data: bytes):
+            body.write(f'--{boundary}\r\n'.encode())
+            body.write(f'Content-Disposition: form-data; name="{name}"; filename="{fname}"\r\n'.encode())
+            body.write(b'Content-Type: application/octet-stream\r\n\r\n')
+            body.write(data)
+            body.write(b'\r\n')
+
+        add_field('chat_id', self.chat_id)
+        if self.thread_id is not None:
+            add_field('message_thread_id', str(self.thread_id))
+        if caption:
+            add_field('caption', caption)
+        add_file('document', filename, file_bytes)
+        body.write(f'--{boundary}--\r\n'.encode())
+
+        req = urllib.request.Request(
+            url, data=body.getvalue(),
+            headers={'Content-Type': f'multipart/form-data; boundary={boundary}'},
+        )
+        with urllib.request.urlopen(req, timeout=60) as resp:
+            result = json.loads(resp.read())
+        return str(result.get('result', {}).get('message_id', ''))
+
     def edit(self, message_id: str, text: str) -> None:
         """Edit an existing message in-place."""
         try: