fix(telegram): guard against empty text in editMessageText

[piorpua]

Summary

• Fix GrammyError: Call to 'editMessageText' failed! (400: Bad Request: text must be non-empty) when streaming AI responses via Telegram channel
• Whitespace-only content (e.g. '\n\n') passed JavaScript truthy checks but was rejected by Telegram API as empty text
• Add trim() check in ActionExecutor.convertTMessageToOutgoing() to replace whitespace-only text with '...' placeholder
• Add guard in TelegramPlugin.editMessage() to skip the API call when text is empty or whitespace-only

Test plan

• Start dev environment and connect a Telegram channel
• Send a message that triggers AI streaming response
• Verify console no longer shows text must be non-empty errors
• Verify messages display correctly with streaming updates working as expected
• Verify non-Telegram channels are unaffected

[github-actions]

Code Review

MEDIUM Issues

1. Potential runtime error if formatTextForPlatform() ever returns a non-string

File: src/channels/gateway/ActionExecutor.ts:157-160

const rawText = formatTextForPlatform(message.content.content || '', platform);
const text = rawText.trim() ? rawText : '...';

Problem: rawText.trim() assumes formatTextForPlatform() always returns a string. Today it does, but this is a fragile contract: if any future platform formatter accidentally returns null/undefined (or a non-string), this will throw at runtime during streaming and break message delivery.

Fix: Make the guard resilient by normalizing to string before trimming.

const rawText = formatTextForPlatform(message.content.content || '', platform) ?? '';
const normalized = String(rawText);
const text = normalized.trim() ? normalized : '...';

(If you want to keep types tighter, ensure formatTextForPlatform cannot return anything but string and keep the ?? ''.)

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Summary

Level	Count
CRITICAL	0
HIGH	0
MEDIUM	1

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🤖 This review was generated by AI and may contain inaccuracies. Please focus on issues you agree with and feel free to disregard any that seem incorrect. Thank you for your contribution!