feat: add fileset resource type support

Add a new "fileset" resource type that represents a collection of files
stored as a relpath→content map. This enables resource types to manage
multiple files (e.g., config directories, template sets) instead of just
a single file.

Backend:
- Add is_fileset column to resource_type table
- Update CRUD operations and workspace duplication to handle is_fileset
- Add integration tests for fileset resource types

Frontend:
- Add FilesetEditor component with file explorer + Monaco editor
- Extract shared FileExplorer component from RawAppSidebar (dedup)
- Add fileset toggle to EditableSchemaWrapper
- Show fileset editor in ResourceEditor and ApiConnectForm
- Show folder icon for fileset resource types in IconedResourceType

CLI:
- Support fileset resources in sync pull (expand to .fileset/ directory)
- Support fileset resources in sync push (reconstruct from directory)
- Handle !inline_fileset YAML tag in resource resolution

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cli/src/utils/utils.ts

@@ -154,6 +154,10 @@ export function isFileResource(path: string): boolean {
   );
 }
 
+export function isFilesetResource(path: string): boolean {
+  return path.includes(".fileset/") || path.includes(".fileset\\");
+}
+
 export function isRawAppFile(path: string): boolean {
   return isRawAppPath(path);
 }