admin: mark ghost users (no DB account) and add Delete dir button

- /api/admin/disk now includes in_db flag per user (true if account exists in DB)
- Ghost users (directory exists, no DB account) show amber 'ghost' badge and only
  Diag + Delete dir buttons (no Re-extract, Rebuild, Reset pwd, Reset data)
- DELETE /api/admin/users/{handle}/directory wipes the entire directory and updates
  the root manifest; refuses if the account still exists in the DB
- Wires up rmdir-btn with a window.confirm before calling the new endpoint

bincio/serve/server.py

@@ -509,6 +509,8 @@ async def admin_disk(bincio_session: Optional[str] = Cookie(default=None)) -> JS
             return 0
         return sum(1 for f in path.glob(pattern) if f.is_file())
 
+    db = _get_db()
+    from bincio.serve.db import get_user as _get_user
     users = []
     for user_dir in sorted(data_dir.iterdir()):
         if not user_dir.is_dir() or user_dir.name.startswith("_"):
@@ -517,6 +519,7 @@ async def admin_disk(bincio_session: Optional[str] = Cookie(default=None)) -> JS
         leaked = [f for f in user_dir.glob("tmp*.zip") if f.is_file()]
         users.append({
             "handle": user_dir.name,
+            "in_db": _get_user(db, user_dir.name) is not None,
             "total_mb": _mb(user_dir),
             "activities_mb": _mb(user_dir / "activities"),
             "activities_count": _count(user_dir / "activities", "*.json"),
@@ -850,6 +853,38 @@ async def admin_delete_activities(
     return JSONResponse({"ok": True, "deleted": deleted})
 
 
+@app.delete("/api/admin/users/{handle}/directory")
+async def admin_delete_user_directory(
+    handle: str,
+    bincio_session: Optional[str] = Cookie(default=None),
+) -> JSONResponse:
+    """Delete the entire user directory from disk (for ghost users not in the DB).
+
+    Refuses if the handle exists as an account in the database — use
+    DELETE /api/admin/users/{handle}/activities for registered users.
+    """
+    import shutil
+    _require_admin(bincio_session)
+    db = _get_db()
+    from bincio.serve.db import get_user as _get_user
+    if _get_user(db, handle) is not None:
+        raise HTTPException(
+            400,
+            f"User '{handle}' is still in the database. Remove the account first, "
+            "or use 'Reset data' to wipe only activity files.",
+        )
+    user_dir = _get_data_dir() / handle
+    if not user_dir.is_dir():
+        raise HTTPException(404, f"No directory for '{handle}'")
+    shutil.rmtree(user_dir)
+    # Rebuild root manifest so the ghost shard disappears from the site
+    from bincio.render.cli import _write_root_manifest
+    try:
+        _write_root_manifest(_get_data_dir())
+    except Exception:
+        pass
+    return JSONResponse({"ok": True})
+
 
 
 # ── Write API (ported from bincio edit, auth-gated) ───────────────────────────