feat(beads): add queue bead type

Add queue bead type for tracking work queues in Gas Town. This includes:
- QueueFields struct with status, concurrency, processing order, and counts
- Parse/Format functions for queue field serialization
- CRUD methods: CreateQueueBead, GetQueueBead, UpdateQueueFields, etc.
- Queue registered in BeadsCustomTypes for bd CLI support

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

internal/constants/constants.go

@@ -83,12 +83,12 @@ const (
 	// BeadsCustomTypes is the comma-separated list of custom issue types that
 	// Gas Town registers with beads. These types were extracted from beads core
 	// in v0.46.0 and now require explicit configuration.
-	BeadsCustomTypes = "agent,role,rig,convoy,slot"
+	BeadsCustomTypes = "agent,role,rig,convoy,slot,queue"
 )
 
 // BeadsCustomTypesList returns the custom types as a slice.
 func BeadsCustomTypesList() []string {
-	return []string{"agent", "role", "rig", "convoy", "slot"}
+	return []string{"agent", "role", "rig", "convoy", "slot", "queue"}
 }
 
 // Git branch names.