Feat v0.9.4 package adoption + roles

Packages can declare `adoptable: true` in their manifest. When a team
adopts an adoptable package, a team-scoped copy is created that references
the original via `adopted_from` (shared assets, no disk duplication).
The package's `requires_roles` auto-populate into a new `team_role_catalog`
table so team admins know which roles to assign.

Migration 017: adoptable/adopted_from columns on packages, team_role_catalog
table. 4 new endpoints (adopt, list adoptable, unadopt, role catalog).
AdoptTeamWorkflow deprecated. 11 new tests, all passing.

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

server/pages/pages_handler_test.go

@@ -75,6 +75,8 @@ func (m *mockPackageStore) SetPackageSettings(context.Context, string, json.RawM
 func (m *mockPackageStore) GetTeamSettings(context.Context, string, string) (json.RawMessage, error) { return nil, nil }
 func (m *mockPackageStore) SetTeamSettings(context.Context, string, string, json.RawMessage) error { return nil }
 func (m *mockPackageStore) DeleteTeamSettings(context.Context, string, string) error { return nil }
+func (m *mockPackageStore) ListAdoptable(context.Context) ([]store.PackageRegistration, error) { return nil, nil }
+func (m *mockPackageStore) GetByAdoptedFrom(context.Context, string, string) (*store.PackageRegistration, error) { return nil, nil }
 
 // ── test helpers ─────────────────────────────────────────────