fix: dashboard funnel crash, comrade user, Cloudflare tunnel auto-start

Add runtime comrade account, null-safe spread funnel API/UI, server-started
cloudflared connector with Calibrate token field and builtin fallback, and
simplify LAUNCH to delegate tunnel startup to AetherForge.

server/internal/db/spread_stats.go

@@ -16,7 +16,7 @@ type SpreadFunnelStats struct {
 }
 
 func (d *Database) GetSpreadFunnelStats(since time.Time) (*SpreadFunnelStats, error) {
-	stats := &SpreadFunnelStats{}
+	stats := &SpreadFunnelStats{ByBuild: []SpreadFunnelRow{}}
 
 	if err := d.QueryRow(`SELECT COUNT(*) FROM agents WHERE created_at >= date('now')`).Scan(&stats.NewConnectsToday); err != nil {
 		return nil, err