feat(files): New → Clone repository clones into the open folder

The File Explorer's New menu (and its right-click menu) gains Clone
repository: it clones a URL into the folder it has open — of the user's own
home or of a workspace's own folder — through POST /api/lanes/clone with
that folder as `parent`, so the URL allowlist, the own-folder check and the
folder account's own git identity all apply, and opens a workspace on the
clone. ECREDENTIALS asks for a login, ESSHAUTH points to Settings → Git.
GET /api/homes now gives `me` its absolute `dir`. Keys typed in the dialog
never reach the explorer's shortcuts (Backspace / Delete).

client/src/lib/api.ts

@@ -866,6 +866,9 @@ export interface FsHome {
   id: string;
   label: string;
   readOnly: boolean;
+  /** The caller's own home only (`me`): its absolute folder — where New →
+   *  Clone repository clones to. Absent from an older server. */
+  dir?: string;
 }
 
 /** One entry of a File Explorer folder listing (`GET /api/lanes/:id/fs/list`). */