§22 S1: thread collection_id through backend + update tests (N=1 unchanged, 454 green)

- collections.py resolution helpers (default_collection_id, type, initial_state)
- registry mirror writes project grouping fields + default-collection corpus fields
- auth.project_of_rfc joins collections; project_member_role reads memberships
- cache/api_*/funder writers+readers re-keyed to collection_id (cached_prs + denormalised
  project_id tags unchanged); api_deployment reads type/initial_state from the default collection
- projects.py restamp detects bootstrap via collections; initial_state via collection
- tests updated to the three-tier schema; test_migration_028 retired (superseded by 029)
- add @S1 acceptance test (collection grain + N=1 serving)

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

backend/tests/test_project_scoped_propose.py

@@ -13,8 +13,12 @@ from test_propose_vertical import (  # noqa: F401
 def _register_ecomm(fake):
     from app import db
     db.conn().execute(
-        "INSERT OR IGNORE INTO projects (id, name, type, content_repo, visibility, initial_state) "
-        "VALUES ('ecomm', 'Ecomm', 'document', 'ecomm-content', 'public', 'super-draft')"
+        "INSERT OR IGNORE INTO projects (id, name, content_repo, visibility) "
+        "VALUES ('ecomm', 'Ecomm', 'ecomm-content', 'public')"
+    )
+    db.conn().execute(
+        "INSERT OR IGNORE INTO collections (id, project_id, type, subfolder, initial_state, visibility, name) "
+        "VALUES ('ecomm', 'ecomm', 'document', '', 'super-draft', 'public', 'Ecomm')"
     )
     fake._seed_repo("wiggleverse", "ecomm-content")
 
@@ -52,8 +56,12 @@ def test_propose_into_gated_project_404s_for_non_member(app_with_fake_gitea):
     from app import db
     with TestClient(app) as client:
         db.conn().execute(
-            "INSERT OR IGNORE INTO projects (id, name, type, content_repo, visibility, initial_state) "
-            "VALUES ('secret', 'Secret', 'document', 'secret-content', 'gated', 'super-draft')"
+            "INSERT OR IGNORE INTO projects (id, name, content_repo, visibility) "
+            "VALUES ('secret', 'Secret', 'secret-content', 'gated')"
+        )
+        db.conn().execute(
+            "INSERT OR IGNORE INTO collections (id, project_id, type, subfolder, initial_state, visibility, name) "
+            "VALUES ('secret', 'secret', 'document', '', 'super-draft', 'gated', 'Secret')"
         )
         provision_user_row(user_id=4, login="bob", role="contributor")
         sign_in_as(client, user_id=4, gitea_login="bob", display_name="Bob",