feat: Wire MQ lifecycle events to gt feed display (gt-lak31)

- Add MQ event types and logging in mrqueue/events.go
- Have refinery emit merge_started, merged, merge_failed, merge_skipped events
- Create MQEventSource to read from mq_events.jsonl
- Add MultiSource to combine events from bd activity and MQ events
- Add color coding: green for merged, red for failed
- Update feed help with MQ event symbols

Events are stored in .beads/mq_events.jsonl and displayed in the feed TUI
with appropriate symbols and colors.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/mrqueue/events_test.go

@@ -0,0 +1,114 @@
+package mrqueue
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+)
+
+func TestEventLogger(t *testing.T) {
+	// Create temp directory
+	tmpDir, err := os.MkdirTemp("", "mrqueue-test")
+	if err != nil {
+		t.Fatalf("Failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	beadsDir := filepath.Join(tmpDir, ".beads")
+	if err := os.MkdirAll(beadsDir, 0755); err != nil {
+		t.Fatalf("Failed to create beads dir: %v", err)
+	}
+
+	logger := NewEventLogger(beadsDir)
+
+	// Test MR
+	mr := &MR{
+		ID:          "mr-test-123",
+		Branch:      "polecat/test",
+		Target:      "main",
+		SourceIssue: "gt-abc",
+		Worker:      "test-worker",
+		Rig:         "test-rig",
+	}
+
+	// Log merge_started
+	if err := logger.LogMergeStarted(mr); err != nil {
+		t.Errorf("LogMergeStarted failed: %v", err)
+	}
+
+	// Log merged
+	if err := logger.LogMerged(mr, "abc123def456"); err != nil {
+		t.Errorf("LogMerged failed: %v", err)
+	}
+
+	// Log merge_failed
+	if err := logger.LogMergeFailed(mr, "conflict in file.go"); err != nil {
+		t.Errorf("LogMergeFailed failed: %v", err)
+	}
+
+	// Log merge_skipped
+	if err := logger.LogMergeSkipped(mr, "already merged"); err != nil {
+		t.Errorf("LogMergeSkipped failed: %v", err)
+	}
+
+	// Read and verify events
+	logPath := logger.LogPath()
+	data, err := os.ReadFile(logPath)
+	if err != nil {
+		t.Fatalf("Failed to read log file: %v", err)
+	}
+
+	lines := splitLines(string(data))
+	if len(lines) != 4 {
+		t.Errorf("Expected 4 events, got %d", len(lines))
+	}
+
+	// Verify each event type
+	expectedTypes := []EventType{EventMergeStarted, EventMerged, EventMergeFailed, EventMergeSkipped}
+	for i, line := range lines {
+		if line == "" {
+			continue
+		}
+		var event Event
+		if err := json.Unmarshal([]byte(line), &event); err != nil {
+			t.Errorf("Failed to parse event %d: %v", i, err)
+			continue
+		}
+
+		if event.Type != expectedTypes[i] {
+			t.Errorf("Event %d: expected type %s, got %s", i, expectedTypes[i], event.Type)
+		}
+
+		if event.MRID != mr.ID {
+			t.Errorf("Event %d: expected MR ID %s, got %s", i, mr.ID, event.MRID)
+		}
+
+		if event.Branch != mr.Branch {
+			t.Errorf("Event %d: expected branch %s, got %s", i, mr.Branch, event.Branch)
+		}
+
+		// Check timestamp is recent
+		if time.Since(event.Timestamp) > time.Minute {
+			t.Errorf("Event %d: timestamp too old: %v", i, event.Timestamp)
+		}
+	}
+}
+
+func splitLines(s string) []string {
+	var lines []string
+	start := 0
+	for i := 0; i < len(s); i++ {
+		if s[i] == '\n' {
+			if start < i {
+				lines = append(lines, s[start:i])
+			}
+			start = i + 1
+		}
+	}
+	if start < len(s) {
+		lines = append(lines, s[start:])
+	}
+	return lines
+}