Feat v0.9.3 team user roles

Promote team roles to a kernel primitive with many-to-many support.
Users can now hold multiple roles within a team simultaneously.

- Migration 016: team_user_roles table (both dialects)
- 6 new TeamStore methods (AddUserRole, RemoveUserRole, ListUserRoles,
  GetMemberRoles, HasRole, RemoveAllUserRoles)
- RequireRole() middleware with OR semantics and system admin bypass
- 3 new handler endpoints for member role CRUD
- Manifest requires_roles field (advisory for v0.9.3)
- Starlark teams module: get_member_roles(), has_role()
- Team-admin UI: role badge chips + assignment dropdown
- Fixed pre-existing SDK auto-unwrap bug in loadRoles
- 10 new tests

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

server/handlers/package_validate.go

@@ -33,6 +33,7 @@ type ManifestInfo struct {
 	Signature       string // reserved for future package signing
 	UserPermissions []string // user-facing permissions declared by the extension
 	GatePermission  string   // if set, checks this user permission before calling on_request
+	RequiresRoles   []string // team roles needed to access this package (advisory, OR semantics)
 }
 
 // ValidateManifest parses a manifest map and validates all required fields,
@@ -168,6 +169,15 @@ func ValidateManifest(manifest map[string]any) (*ManifestInfo, error) {
 	}
 	info.GatePermission, _ = manifest["gate_permission"].(string)
 
+	// v0.9.3: requires_roles — team roles needed to access this package (advisory)
+	if rr, ok := manifest["requires_roles"].([]any); ok {
+		for _, v := range rr {
+			if s, ok := v.(string); ok && s != "" && len(s) <= 50 {
+				info.RequiresRoles = append(info.RequiresRoles, s)
+			}
+		}
+	}
+
 	info.SchemaVersion = ParseSchemaVersion(manifest)
 
 	// ── Type-specific constraints ────────────────────────────────