fix(channels): make tool feedback edit throttle configurable

[bogdanovich]

Summary

Make editable tool feedback progress throttling configurable instead of hard-coding a new behavior into all channels.

This adds two agents.defaults.tool_feedback settings:

• animation_interval_secs controls the progress animation edit interval. It defaults to 3, preserving the existing animation cadence.
• edit_min_interval_seconds controls the minimum interval between edits of the same tracked progress message. It defaults to 0, preserving legacy behavior with no edit throttle.

When edit_min_interval_seconds is enabled, the animator coalesces rapid updates into its tracked state instead of immediately editing the same message again. It also honors Telegram-style retry after N / 429 rate-limit errors by temporarily pausing edits for that tracked message.

Why

Some chat platforms share message send/edit limits. Long-running tool feedback, especially with concurrent turns or subagents, can otherwise hit platform rate limits and delay or orphan progress cleanup. Making the throttle configurable lets deployments opt in without changing default behavior for existing channels.

Backward compatibility

Defaults preserve existing behavior:

{
  "agents": {
    "defaults": {
      "tool_feedback": {
        "animation_interval_secs": 3,
        "edit_min_interval_seconds": 0
      }
    }
  }
}

Testing

• go test ./pkg/channels
• go test ./pkg/channels/telegram ./pkg/channels/discord ./pkg/channels/pico
• go test ./pkg/channels/feishu
• go test ./pkg/config
• go test ./pkg/agent
• make build

Note: direct go test ./pkg/channels/matrix cannot run in this environment because the system olm/olm.h header is unavailable, but make build succeeds.