fix(ton-bridge): replace inlineKeyboard URL buttons with embedded text links

[konard]

Problem

All three TON Bridge tools (ton_bridge_open, ton_bridge_about, ton_bridge_custom_message) crash with:

TypeError [ERR_INVALID_ARG_TYPE]: The first argument must be of type string or an instance of Buffer, ArrayBuffer, or Array or an Array-like Object. Received undefined
    at Buffer.from (node:buffer:348:9)

Root cause

The agent's TelegramBridge.sendMessage implementation iterates over inlineKeyboard buttons and calls Buffer.from(button.callback_data) to serialize button data. The TON Bridge plugin passes URL buttons ({ text, url }) which don't have callback_data — so Buffer.from(undefined) is called, causing the crash.

The SDK documentation (CONTRIBUTING.md, references/patterns.md) only shows callback_data buttons in inlineKeyboard examples. No other plugin in the repo uses URL buttons — only callback_data buttons are supported.

Fix

Replace inlineKeyboard URL buttons with the Mini App link embedded directly in the message text via a new buildMessageWithLink() helper. The https://t.me/TONBridge_robot?startapp deep link renders as a tappable link in Telegram messages across DMs, groups, and channels.

Before (crashes):

await sdk.telegram.sendMessage(context.chatId, text, {
  inlineKeyboard: [[{ text: buttonText, url }]],  // ← URL button unsupported
});

After (works):

const fullText = buildMessageWithLink(text, buttonText, url);
await sdk.telegram.sendMessage(context.chatId, fullText);

Tests

All 28 tests pass. Updated tests verify:

• Link is embedded in message text (not in inlineKeyboard)
• No inlineKeyboard options passed to sendMessage
• Custom button text and startParam still appear correctly in the message
• Fallback chains for missing params still work

Fixes #33

🤖 Generated with Claude Code

[konard]

🤖 Solution Draft Log

This log file contains the complete execution trace of the AI solution draft process.

💰 Cost estimation:

• Public pricing estimate: $2.652093
• Calculated by Anthropic: $1.778211 USD
• Difference: $-0.873882 (-32.95%)

🤖 Models used:

• Tool: Claude
• Requested: opus
• Main model: Claude Opus 4.6 (claude-opus-4-6)
• Additional models:
  • Claude Haiku 4.5 (claude-haiku-4-5-20251001)

📎 Log file uploaded as Gist (1207KB)

• View complete solution draft log

---

Now working session is ended, feel free to review and add any feedback on the solution draft.

[konard]

✅ Ready to merge

This pull request is now ready to be merged:

• All CI checks have passed
• No merge conflicts
• No pending changes

---

Monitored by hive-mind with --auto-restart-until-mergeable flag