feat(shared-queues): materialized competing consumers + dispatcher branch (D3.2)

The consumption side of shared durable queues:
- Thread `shared` through BundleTrigger::Queue + QueueTriggerSpec + the
  trigger identity; validate_bundle_for requires a shared queue on a group
  to name a declared kind='queue' collection (a shared queue on an app is
  rejected by the existing app-owner shared guard).
- materialize: a shared queue template materializes a consumer per
  descendant (the M5 one-consumer-slot skip is bypassed for shared —
  competing consumers are intended; each descendant gets one copy).
- dispatcher: ActiveQueueConsumer gains shared_group (from the materialized
  copy's source template via LEFT JOIN); dispatch_one_queue +
  handle_queue_failure route claim/ack/nack/terminal to the group store
  when shared_group is Some, via q_claim/q_ack/q_nack/q_terminal helpers. A
  group claim is normalized to a ClaimedMessage under the consuming app so
  the handler path is unchanged; the reclaim task also drains the group
  store. Exhausted shared messages are dropped (no group dead-letter store
  yet — documented deferral).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/manager-core/src/apply_service.rs

@@ -260,6 +260,10 @@ pub enum BundleTrigger {
         dispatch_mode: Option<TriggerDispatchMode>,
         #[serde(default)]
         retry_max_attempts: Option<u32>,
+        /// §11.6 D3: `true` for a shared-QUEUE group consumer — materializes a
+        /// competing consumer per descendant app, all claiming the group store.
+        #[serde(default)]
+        shared: bool,
     },
 }
 
@@ -313,8 +317,9 @@ impl BundleTrigger {
             Self::Kv { shared, .. }
             | Self::Docs { shared, .. }
             | Self::Files { shared, .. }
-            | Self::Pubsub { shared, .. } => *shared,
-            Self::Cron { .. } | Self::Email { .. } | Self::Queue { .. } => false,
+            | Self::Pubsub { shared, .. }
+            | Self::Queue { shared, .. } => *shared,
+            Self::Cron { .. } | Self::Email { .. } => false,
         }
     }
 
@@ -390,7 +395,9 @@ impl BundleTrigger {
                 ..
             } => format!("pubsub|{script}|{topic_pattern}|{sealed}|{shared}"),
             Self::Email { script, .. } => format!("email|{script}"),
-            Self::Queue { queue_name, .. } => format!("queue|{queue_name}"),
+            Self::Queue {
+                queue_name, shared, ..
+            } => format!("queue|{queue_name}|{shared}"),
         }
     }
 
@@ -787,9 +794,10 @@ impl ApplyService {
                         BundleTrigger::Pubsub { topic_pattern, .. } => {
                             (topic_pattern.split('.').next().unwrap_or(""), "topic")
                         }
+                        BundleTrigger::Queue { queue_name, .. } => (queue_name.as_str(), "queue"),
                         _ => {
                             return Err(ApplyError::Invalid(format!(
-                                "a `shared` trigger must be a kv/docs/files/pubsub kind; \
+                                "a `shared` trigger must be a kv/docs/files/pubsub/queue kind; \
                                  `{}` has no shared collection store",
                                 t.kind_str()
                             )));
@@ -3416,7 +3424,7 @@ fn current_trigger_identity(t: &Trigger, name_by_id: &HashMap<ScriptId, String>)
             Some(format!("pubsub|{script}|{topic_pattern}|{sealed}|{shared}"))
         }
         TriggerDetails::Email { .. } => Some(format!("email|{script}")),
-        TriggerDetails::Queue { queue_name, .. } => Some(format!("queue|{queue_name}")),
+        TriggerDetails::Queue { queue_name, .. } => Some(format!("queue|{queue_name}|{shared}")),
         TriggerDetails::DeadLetter { .. } => None,
     }
 }
@@ -4254,6 +4262,7 @@ mod tests {
             visibility_timeout_secs: vis,
             dispatch_mode: None,
             retry_max_attempts: None,
+            shared: false,
         };
         assert!(validate_trigger_shape(&queue(Some(10))).is_err());
         assert!(validate_trigger_shape(&queue(Some(
@@ -4715,6 +4724,7 @@ mod tests {
             visibility_timeout_secs: None,
             dispatch_mode: None,
             retry_max_attempts: None,
+            shared: false,
         }];
         let p = compute_diff(&current, &b);
         assert!(