feat: add file/photo sending to Telegram bot

[Fenrur]

Summary

• Adds [file:/path/to/file] directive support in Claude's responses to send local files via Telegram
• Images (png, jpg, jpeg, gif, webp) are sent via sendPhoto API; all other files via sendDocument API
• Uses Bun's native FormData and Blob — zero new dependencies
• Graceful error handling: if a file doesn't exist or upload fails, sends an error message to the chat instead of crashing

How it works

When Claude includes [file:/absolute/path/to/file.png] in its response:

1. The directive is extracted and stripped from the displayed text
2. The file extension determines whether to use sendPhoto or sendDocument
3. The file is uploaded via multipart/form-data to the Telegram Bot API
4. The remaining text is sent as a normal message

Functions added

• sendPhotoFile() — uploads an image via Telegram's sendPhoto endpoint
• sendFileDocument() — uploads any file via Telegram's sendDocument endpoint
• sendLocalFile() — auto-routes to photo or document based on extension
• extractFileDirectives() — parses [file:/path] patterns from response text

Test plan

• Send a message that triggers Claude to respond with [file:/path/to/image.png] → image is sent as photo
• Send a message with [file:/path/to/doc.pdf] → file is sent as document
• Test with a non-existent path → error message sent gracefully
• Test with multiple [file:...] directives in one response
• Verify remaining text is still sent correctly after directives are stripped
• Verify existing functionality (reactions, typing, etc.) is unchanged

🤖 Generated with Claude Code