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/tools/send_file.py

@@ -0,0 +1,20 @@
+"""Send file tool — sends documents to the user via Telegram."""
+from tools import messaging
+
+
+def send_file(file_content: str, filename: str, caption: str = '') -> str:
+    """Send a file to the user as a Telegram document attachment.
+
+    Args:
+        file_content: The text content of the file to send.
+        filename: The filename (e.g. 'report.txt', 'data.csv').
+        caption: Optional caption to display with the file.
+    """
+    adapter = messaging._adapter
+    if adapter is None:
+        return 'No channel adapter configured.'
+    if not hasattr(adapter, 'send_document'):
+        return 'Channel adapter does not support file sending.'
+    file_bytes = file_content.encode('utf-8')
+    msg_id = adapter.send_document(file_bytes, filename, caption)
+    return f'File "{filename}" sent (id={msg_id})' if msg_id else f'File "{filename}" sent'