#22431: feat(hooks): add channel:connected hook event

## Summary Adds a `channel:connected` hook event that fires when a WhatsApp channel successfully connects. This enables custom automation on reconnect — for example, sending a "bot is back online" notification to the user. ## Changes - `src/hooks/internal-hooks.ts`: Add `ChannelConnectedHookContext`, `ChannelConnectedHookEvent` types and `isChannelConnectedEvent` guard - `src/web/auto-reply/monitor.ts`: Fire `channel:connected` hook on successful WhatsApp connect ## Usage ```ts // In a hook handler: if (isChannelConnectedEvent(event)) { // event.context.channel === "whatsapp" // event.context.accountId === the account that connected await sendMessage({ message: "Bot reconnected! 🤖" }); } ``` Fixes the motivation from #7405 — allows agents to react to channel reconnects proactively. <!-- greptile_comment --> <h3>Greptile Summary</h3> Adds a new `channel:connected` hook event that fires when a WhatsApp channel successfully connects, enabling custom automation on reconnect (e.g., sending "bot is back online" notifications). - Added type definitions for `ChannelConnectedHookContext` and `ChannelConnectedHookEvent` with proper JSDoc documentation - Implemented `isChannelConnectedEvent` guard function following existing validation patterns - Integrated hook trigger in `monitor.ts` after successful WhatsApp connection, consistent with other event patterns - All types are properly exported and match the documented API in the PR description <h3>Confidence Score: 5/5</h3> - This PR is safe to merge with minimal risk - The implementation follows established patterns precisely, adds well-documented types, and integrates cleanly at the appropriate location. The changes are focused, non-breaking, and purely additive. - No files require special attention _{Last reviewed commit: cc9db95} <!-- greptile_other_comments_section --> _{(3/5) Reply to the agent's comments like "Can you suggest a fix for this @greptileai?" or ask follow-up questions!} <!-- /greptile_comment -->