feat(projects): projects table + owner_project FK; ProjectId/Project types

First commit of §7 multi-repo ownership. A 'project' is a repo-root that
declaratively manages a slice of the shared group tree; each group node is
owned by exactly one project (single-owner-per-node). This lands the registry
+ shared types and wires the inert 0047 `owner_project` seam — no behavior
change yet (claim logic is the next commit).

- migration 0066: `projects` table (UUID pk, unique slug, name, created_by →
  admin_users ON DELETE SET NULL); `groups.owner_project` gains its FK →
  projects(id) ON DELETE SET NULL (un-claim, never cascade-destroy a tree) +
  an index.
- shared: `ProjectId` (id_type! macro) + `Project` struct; `Group` gains
  `owner_project: Option<ProjectId>`.
- group_repo: GROUP_COLS + the ancestors recursive-CTE term now carry
  `owner_project`, so `ancestors()` surfaces ownership for the nearest-claimed
  fold; GroupRow + From updated.
- schema snapshot re-blessed; /version schema assertion 65 → 66.

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

crates/manager-core/tests/expected_schema.txt

@@ -318,6 +318,13 @@ table: outbox
   claimed_by: text NULL
   created_at: timestamp with time zone NOT NULL default=now()
 
+table: projects
+  id: uuid NOT NULL default=gen_random_uuid()
+  slug: text NOT NULL
+  name: text NOT NULL
+  created_by: uuid NULL
+  created_at: timestamp with time zone NOT NULL default=now()
+
 table: pubsub_trigger_details
   trigger_id: uuid NOT NULL
   topic_pattern: text NOT NULL
@@ -579,6 +586,7 @@ indexes on group_queue_messages:
   idx_group_queue_messages_group_collection: public.group_queue_messages USING btree (group_id, collection)
 
 indexes on groups:
+  groups_owner_project_idx: public.groups USING btree (owner_project)
   groups_parent_id_idx: public.groups USING btree (parent_id)
   groups_pkey: public.groups USING btree (id)
   groups_slug_key: public.groups USING btree (slug)
@@ -595,6 +603,10 @@ indexes on outbox:
   idx_outbox_due: public.outbox USING btree (next_attempt_at) WHERE (claimed_at IS NULL)
   outbox_pkey: public.outbox USING btree (id)
 
+indexes on projects:
+  projects_pkey: public.projects USING btree (id)
+  projects_slug_key: public.projects USING btree (slug)
+
 indexes on pubsub_trigger_details:
   pubsub_trigger_details_pkey: public.pubsub_trigger_details USING btree (trigger_id)
 
@@ -817,6 +829,7 @@ constraints on group_queue_messages:
   [PRIMARY KEY] group_queue_messages_pkey: PRIMARY KEY (id)
 
 constraints on groups:
+  [FOREIGN KEY] groups_owner_project_fk: FOREIGN KEY (owner_project) REFERENCES projects(id) ON DELETE SET NULL
   [FOREIGN KEY] groups_parent_id_fkey: FOREIGN KEY (parent_id) REFERENCES groups(id) ON DELETE RESTRICT
   [PRIMARY KEY] groups_pkey: PRIMARY KEY (id)
   [UNIQUE] groups_slug_key: UNIQUE (slug)
@@ -834,6 +847,11 @@ constraints on outbox:
   [FOREIGN KEY] outbox_app_id_fkey: FOREIGN KEY (app_id) REFERENCES apps(id) ON DELETE CASCADE
   [PRIMARY KEY] outbox_pkey: PRIMARY KEY (id)
 
+constraints on projects:
+  [FOREIGN KEY] projects_created_by_fkey: FOREIGN KEY (created_by) REFERENCES admin_users(id) ON DELETE SET NULL
+  [PRIMARY KEY] projects_pkey: PRIMARY KEY (id)
+  [UNIQUE] projects_slug_key: UNIQUE (slug)
+
 constraints on pubsub_trigger_details:
   [FOREIGN KEY] pubsub_trigger_details_trigger_id_fkey: FOREIGN KEY (trigger_id) REFERENCES triggers(id) ON DELETE CASCADE
   [PRIMARY KEY] pubsub_trigger_details_pkey: PRIMARY KEY (trigger_id)
@@ -973,3 +991,4 @@ constraints on vars:
   0063: materialized unique
   0064: shared topic queue kinds
   0065: group queues
+  0066: projects