feat: TUI progress visibility for council reviews

[skwid138]

Summary

When a council review is in progress, the user has no visibility into what's happening in the TUI. Reviews can take 60-180+ seconds, and the only feedback is silence until the aggregated result appears (or an error surfaces). The recently added debug logging helps developers diagnose issues but is not a user-facing progress indicator.

Desired Behavior

Provide real-time progress feedback in the TUI during council reviews, such as:

• "Council review started — dispatching to N models..."
• "Reviewer 1/N responded (model-name)" as each completes
• "Waiting for M remaining reviewers..." with elapsed time
• "Aggregating responses..." when the aggregation phase begins
• Timeout warnings: "Reviewer X approaching timeout (150s/180s)..."

Current State

• The plugin logs structured messages via ctx.client.app.log() when debug: true
• These logs go to opencode's internal log stream, not to user-visible TUI elements
• The council_review tool returns only the final aggregated result or an error string
• No intermediate progress is surfaced to the calling agent or user

Constraints & Considerations

• OpenCode's plugin API may not currently support streaming progress updates to the TUI — this may require upstream API additions or a convention for progress reporting
• The progress messages should be informational, not pollute the conversation history
• Should work regardless of whether debug logging is enabled
• Consider whether this is best implemented as:
  • Plugin-level progress events (if the API supports it)
  • Periodic status messages to the parent session
  • A convention where the tool returns partial results that the calling agent can surface

References

• src/index.ts lines 470-483 (current logging infrastructure)
• OpenCode plugin API documentation for available progress/streaming mechanisms