fix(BA-5795): set main_access_key in component test user fixtures

The admin/regular user fixtures were missing `main_access_key`, causing
`ensure_host_permission_allowed_by_user` to fail with ObjectNotFound
when resolving the user's keypair resource policy. Also fix module
docstring in vfolder_v2.py to not overstate RBAC coverage.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: fregataa

src/ai/backend/manager/services/vfolder/actions/vfolder_v2.py

@@ -1,4 +1,4 @@
-"""V2 vfolder actions — RBAC-enforced via SingleEntityActionProcessor."""
+"""V2 vfolder action definitions."""
 
 import uuid
 from dataclasses import dataclass

tests/component/conftest.py

@@ -770,6 +770,11 @@ async def admin_user_fixture(
                 user=str(data.user_uuid),
             )
         )
+        await conn.execute(
+            users.update()
+            .where(users.c.uuid == str(data.user_uuid))
+            .values(main_access_key=data.keypair.access_key)
+        )
         await conn.execute(
             sa.insert(association_groups_users).values(
                 group_id=str(group_fixture),
@@ -791,6 +796,9 @@ async def admin_user_fixture(
                 association_groups_users.c.user_id == str(data.user_uuid)
             )
         )
+        await conn.execute(
+            users.update().where(users.c.uuid == str(data.user_uuid)).values(main_access_key=None)
+        )
         await conn.execute(
             keypairs.delete().where(keypairs.c.access_key == data.keypair.access_key)
         )
@@ -850,6 +858,11 @@ async def regular_user_fixture(
                 user=str(data.user_uuid),
             )
         )
+        await conn.execute(
+            users.update()
+            .where(users.c.uuid == str(data.user_uuid))
+            .values(main_access_key=data.keypair.access_key)
+        )
         await conn.execute(
             sa.insert(association_groups_users).values(
                 group_id=str(group_fixture),
@@ -868,6 +881,9 @@ async def regular_user_fixture(
                 association_groups_users.c.user_id == str(data.user_uuid)
             )
         )
+        await conn.execute(
+            users.update().where(users.c.uuid == str(data.user_uuid)).values(main_access_key=None)
+        )
         await conn.execute(
             keypairs.delete().where(keypairs.c.access_key == data.keypair.access_key)
         )