feat(locate-db): implement BFS directory walk for scanning with progress reporting

src/app/locate-db.ts

@@ -180,12 +180,27 @@ export async function buildLocateDb(
   signal?.throwIfAborted();
   const sqlite3 = await getSqlite3();
 
-  // ── 1. Recursive PROPFIND on /sd ────────────────────────────────────────
-  const entries = await listDirectory(
-    '/sd', true,
-    bytes => onProgress?.('scanning', bytes),
-    signal,
-  );
+  // ── 1. BFS directory walk with Depth:1 per directory ────────────────────
+  // Depth:infinity is not supported by the device's WebDAV server, so we
+  // walk the tree manually, one directory at a time.
+  const entries: Awaited<ReturnType<typeof listDirectory>> = [];
+  const queue: string[] = ['/sd'];
+  let totalBytes = 0;
+
+  while (queue.length > 0) {
+    signal?.throwIfAborted();
+    const dir = queue.shift()!;
+    let prevBytes = 0;
+    const batch = await listDirectory(dir, false, bytes => {
+      totalBytes += bytes - prevBytes;
+      prevBytes = bytes;
+      onProgress?.('scanning', totalBytes, dir);
+    }, signal);
+    for (const e of batch) {
+      entries.push(e);
+      if (e.type === 'folder') queue.push(e.path);
+    }
+  }
   signal?.throwIfAborted();
 
   // ── 2. Build in-memory DB ───────────────────────────────────────────────