Problem

When context auto-compaction runs on Telegram or Discord, the bot appears completely frozen for 10-30 seconds with no visual feedback. Users have no way to tell if the bot is still working or has crashed.

Current behavior

1. User sends a message in a long conversation
2. Auto-compaction triggers (compressing conversation history)
3. Bot shows no status change — the last reaction (e.g. 🤔 thinking) stays frozen
4. After 10-30s, the bot suddenly responds

This is especially confusing on Telegram where the 🤔 reaction just sits there unchanged.

Expected behavior

The bot should show a distinct status reaction during compaction (e.g. ✍ writing) so users know it's actively working on organizing context, not hung.

Context

The building blocks already exist:

• Compaction events are already emitted via onAgentEvent (stream: "compaction", phase: "start"/"end")
• StatusReactionController already manages emoji lifecycle with debounce, stall detection, and serialized transitions
• These two systems just aren't connected

Proposed fix

PR #35474 bridges the gap by:

• Adding a compacting state to StatusReactionController
• Wiring the existing compaction events to the status reaction system
• Showing ✍ during compaction, then resuming 🤔 when done
• Works on both Telegram and Discord

~39 lines of production code, follows existing patterns exactly.