feat(shared-queues): group-keyed queue store + enqueue service + SDK (D3.1)

The producer side of shared durable queues:
- migration 0065 group_queue_messages (mirrors 0034, keyed by (group_id,
  collection); CASCADE on group delete).
- GroupQueueRepo/PostgresGroupQueueRepo: enqueue + the competing-consumer
  claim (FOR UPDATE SKIP LOCKED) + ack/nack/drop_exhausted/reclaim/depth.
- GroupQueueService trait (shared) + GroupQueueServiceImpl: resolve owning
  group (kind='queue') from cx.app_id's chain, require editor+
  (GroupQueueEnqueue, fails closed on anon), size-cap, enqueue.
- SDK: `queue::shared_collection("name")` -> GroupQueueHandle with
  `.enqueue(msg[, opts])` / `.depth()` / `.depth_pending()`; wired through
  Services + the picloud binary.
- authz: Capability::GroupQueueEnqueue(GroupId), editor+ / script:write.

Deterministic test proves competing consumers claim each message exactly
once. Consumption wiring (materialized consumers + dispatcher branch) lands
in D3.2.

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

crates/manager-core/tests/expected_schema.txt

@@ -264,6 +264,19 @@ table: group_members
   role: text NOT NULL
   created_at: timestamp with time zone NOT NULL default=now()
 
+table: group_queue_messages
+  id: uuid NOT NULL default=gen_random_uuid()
+  group_id: uuid NOT NULL
+  collection: text NOT NULL
+  payload: jsonb NOT NULL
+  enqueued_at: timestamp with time zone NOT NULL default=now()
+  deliver_after: timestamp with time zone NULL
+  claim_token: uuid NULL
+  claimed_at: timestamp with time zone NULL
+  attempt: integer NOT NULL default=0
+  max_attempts: integer NOT NULL default=3
+  enqueued_by_principal: uuid NULL
+
 table: groups
   id: uuid NOT NULL default=gen_random_uuid()
   parent_id: uuid NULL
@@ -559,6 +572,12 @@ indexes on group_members:
   group_members_pkey: public.group_members USING btree (group_id, user_id)
   group_members_user_id_idx: public.group_members USING btree (user_id)
 
+indexes on group_queue_messages:
+  group_queue_messages_pkey: public.group_queue_messages USING btree (id)
+  idx_group_queue_messages_claimed: public.group_queue_messages USING btree (claimed_at) WHERE (claim_token IS NOT NULL)
+  idx_group_queue_messages_dispatch: public.group_queue_messages USING btree (group_id, collection, enqueued_at) WHERE (claim_token IS NULL)
+  idx_group_queue_messages_group_collection: public.group_queue_messages USING btree (group_id, collection)
+
 indexes on groups:
   groups_parent_id_idx: public.groups USING btree (parent_id)
   groups_pkey: public.groups USING btree (id)
@@ -793,6 +812,10 @@ constraints on group_members:
   [FOREIGN KEY] group_members_user_id_fkey: FOREIGN KEY (user_id) REFERENCES admin_users(id) ON DELETE CASCADE
   [PRIMARY KEY] group_members_pkey: PRIMARY KEY (group_id, user_id)
 
+constraints on group_queue_messages:
+  [FOREIGN KEY] group_queue_messages_group_id_fkey: FOREIGN KEY (group_id) REFERENCES groups(id) ON DELETE CASCADE
+  [PRIMARY KEY] group_queue_messages_pkey: PRIMARY KEY (id)
+
 constraints on groups:
   [FOREIGN KEY] groups_parent_id_fkey: FOREIGN KEY (parent_id) REFERENCES groups(id) ON DELETE RESTRICT
   [PRIMARY KEY] groups_pkey: PRIMARY KEY (id)
@@ -949,3 +972,4 @@ constraints on vars:
   0062: materialized triggers
   0063: materialized unique
   0064: shared topic queue kinds
+  0065: group queues