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>

include/naut/script.h

@@ -11,6 +11,50 @@ typedef naut_err (*naut_script_move_file_cb)(void *context,
                                              uint32_t file_index,
                                              const char *destination);
 
+/* Resolve a torrent's labels for `naut.get_labels(id)`. Returns a heap array of
+ * `*count` heap strings (caller frees each string then the array), or NULL with
+ * *count==0 if the torrent has no labels / is unknown. */
+typedef char **(*naut_script_labels_cb)(void *context, uint64_t torrent_id,
+                                        size_t *count);
+
+/* One user-configurable setting a script declares via naut.define_settings. */
+typedef struct {
+    const char *key;            /* stable identifier read by naut.get_setting   */
+    const char *label;          /* human label for the web UI form              */
+    const char *type;           /* "string" | "bool" | "number"                 */
+    const char *default_value;  /* stringified default ("true"/"false" for bool)*/
+} naut_script_setting_def;
+
+/* The script (re)declared its settings schema. The host stores it and renders a
+ * form; `defs` is valid only for the duration of the call. */
+typedef void (*naut_script_define_settings_cb)(void *context,
+                                               const naut_script_setting_def *defs,
+                                               size_t count);
+
+/* Setting value kinds, so the Lua side can push the right type. */
+typedef enum {
+    NAUT_SETTING_STRING = 0,
+    NAUT_SETTING_BOOL = 1,
+    NAUT_SETTING_NUMBER = 2,
+} naut_setting_type;
+
+/* Resolve a setting for `naut.get_setting(key)`: the user-set value if present,
+ * else the declared default. Returns a heap string (caller frees) and sets
+ * *type, or NULL if the key is unknown. */
+typedef char *(*naut_script_get_setting_cb)(void *context, const char *key,
+                                            naut_setting_type *type);
+
+/* Host callbacks the sandboxed script may invoke. Any may be NULL (the matching
+ * naut.* function then reports it is unavailable). `context` is passed back to
+ * each callback. */
+typedef struct {
+    naut_script_move_file_cb       move_file;
+    naut_script_labels_cb          labels;
+    naut_script_define_settings_cb define_settings;
+    naut_script_get_setting_cb     get_setting;
+    void                          *context;
+} naut_script_host;
+
 typedef struct {
     uint64_t queued;
     uint64_t handled;
@@ -20,12 +64,12 @@ typedef struct {
 } naut_script_stats;
 
 /* script_path is loaded before the worker starts. queue_capacity bounds copied
- * events and must be non-zero. The VM owns no filesystem or process APIs. */
+ * events and must be non-zero. The VM owns no filesystem or process APIs. `host`
+ * is copied; its callbacks are invoked from the script worker thread. */
 naut_script *naut_script_create(naut_event_bus *events,
                                 const char *script_path,
                                 size_t queue_capacity,
-                                naut_script_move_file_cb move_file,
-                                void *move_context,
+                                const naut_script_host *host,
                                 naut_err *error);
 void naut_script_destroy(naut_script *script);