feat(dnd): Add notification level control (gt-xmsme)

Implements Do Not Disturb mode for Gas Town agents:

- Add notification_level to agent bead schema (verbose, normal, muted)
- gt dnd [on|off|status] - quick toggle for DND mode
- gt notify [verbose|normal|muted] - fine-grained control
- gt nudge checks target DND status, skips if muted
- --force flag on nudge to override DND

This allows agents (especially Mayor) to mute notifications
during focused work like swarm coordination.

Generated with Claude Code

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

internal/cmd/dnd_test.go

@@ -0,0 +1,33 @@
+package cmd
+
+import (
+	"testing"
+)
+
+func TestAddressToAgentBeadID(t *testing.T) {
+	tests := []struct {
+		address  string
+		expected string
+	}{
+		{"mayor", "gt-mayor"},
+		{"deacon", "gt-deacon"},
+		{"gastown/witness", "gt-gastown-witness"},
+		{"gastown/refinery", "gt-gastown-refinery"},
+		{"gastown/alpha", "gt-gastown-polecat-alpha"},
+		{"gastown/crew/max", "gt-gastown-crew-max"},
+		{"beads/witness", "gt-beads-witness"},
+		{"beads/beta", "gt-beads-polecat-beta"},
+		// Invalid addresses should return empty string
+		{"invalid", ""},
+		{"", ""},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.address, func(t *testing.T) {
+			got := addressToAgentBeadID(tt.address)
+			if got != tt.expected {
+				t.Errorf("addressToAgentBeadID(%q) = %q, want %q", tt.address, got, tt.expected)
+			}
+		})
+	}
+}