nautd/webui: scripting, labels, settings, set-location, pause fix

Session checkpoint on webui-plugin:
- engine dump (nautctl dump) + engine endgame integration
- per-file move locations persistence; torrent-level "Set location"
  with reset/keep-relative/leave-separate handling + residual prune
- Lua: naut.get_labels, define_settings/get_setting (script_host struct)
- daemon-owned labels (category+tags) + taxonomy persistence; webui write-through
- fix: pausing a completed/seeding torrent now sticks (stop wins over result)
- automation tab responsive layout; anime_sort label gating + settings

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/unit/test_download.c

@@ -69,6 +69,20 @@ int main(void) {
     CHECK(got && glen == olen && memcmp(got, orig, olen) == 0);
     free(got);
 
+    /* Existing verified data should be reflected in progress before any peer
+     * requests are made. */
+    st = naut_storage_open(mi.files, mi.num_files, root, &err);
+    CHECK(st && err == NAUT_OK);
+    d = naut_download_create(&mi, st);
+    CHECK(d != NULL);
+    CHECK(naut_download_resume(d) == NAUT_OK);
+    CHECK(naut_download_complete(d));
+    CHECK_EQ(naut_download_pieces_done(d), naut_download_num_pieces(d));
+    CHECK_EQ((long long)naut_download_bytes_done(d), (long long)olen);
+    CHECK(!naut_download_next_request(d, &idx, &begin, &len));
+    naut_download_destroy(d);
+    naut_storage_close(st);
+
     /* The same path with SHA-1 verification offloaded to bounded workers. */
     {
         char t2[] = "/tmp/naut_async_XXXXXX";