fix(gamebook): scroll long passages + DELETE /game/file

Context:
Two issues surfaced with the longer kid stories: (1) long passages were
clipped on screen — the body label wrapped in a fixed 196px band and
the tail was simply cut off; (2) old orphan WAVs (demo + archived
adventures) piled up on the SD with no way to remove them, since the
master had POST /game/file but no delete.

Approach:
Make the gamebook body label scroll vertically so the whole passage
goes by, and add a DELETE verb to /game/file mirroring the POST routing
so the host can clean stale assets off the SD.

Changes:
- display_ui: gamebook body label LV_LABEL_LONG_WRAP ->
  LV_LABEL_LONG_SCROLL_CIRCULAR; body buffer 512 -> 1100 so a full
  ~1000-char passage is held and scrolled, not truncated.
- game_endpoint: new DELETE /game/file?path=sd/<…>|apps/<…> (same
  whitelist/traversal guard as POST; unlink + 200/404).
- ota_server: max_uri_handlers 22 -> 24 for the extra verb.

Impact:
Long passages are fully readable on the LCD (they scroll), and the SD
gamebook folder can be cleaned remotely. Hardware-validated: 121 orphan
files deleted, library still opens 6 stories.

idf_zacus/components/display_ui/display_ui.cpp

@@ -256,7 +256,7 @@ static lv_obj_t *s_gb_body;           // full passage text, wrapped
 static lv_obj_t *s_gb_menu;           // choice lines, bottom
 static volatile bool s_gamebook_open = false;
 static char s_gb_title_buf[64];
-static char s_gb_body_buf[512];
+static char s_gb_body_buf[1100];
 static char s_gb_menu_buf[160];
 
 // ── Gamebook library (tile grid) ────────────────────────────────────────────
@@ -837,7 +837,9 @@ static void build_gamebook_screen(void) {
     s_gb_body = lv_label_create(s_scr_gamebook);
     lv_obj_set_style_text_color(s_gb_body, lv_color_hex(COL_VALUE), 0);
     lv_obj_set_style_text_font(s_gb_body, &lv_font_montserrat_14, 0);
-    lv_label_set_long_mode(s_gb_body, LV_LABEL_LONG_WRAP);
+    // Wrap to width AND scroll vertically so long passages are never clipped:
+    // the whole text scrolls slowly through the band while the WAV narrates it.
+    lv_label_set_long_mode(s_gb_body, LV_LABEL_LONG_SCROLL_CIRCULAR);
     lv_obj_set_size(s_gb_body, DUI_HOR_RES - 24, 196);
     lv_label_set_text(s_gb_body, "");
     lv_obj_align(s_gb_body, LV_ALIGN_TOP_LEFT, 12, 44);

idf_zacus/components/game_endpoint/game_endpoint.c

@@ -1173,6 +1173,43 @@ static esp_err_t handle_file_post(httpd_req_t *req) {
     return send_json(req, "200 OK", resp);
 }
 
+// ─── DELETE /game/file?path=sd/<…>|apps/<…> — remove a staged file ───────────
+// Same path routing/whitelist as the POST handler. Lets the host clean stale
+// assets (e.g. orphan gamebook WAVs) off the SD without reflashing.
+static esp_err_t handle_file_delete(httpd_req_t *req) {
+    char query[160], path_param[96];
+    if (httpd_req_get_url_query_str(req, query, sizeof(query)) != ESP_OK ||
+        httpd_query_key_value(query, "path", path_param,
+                              sizeof(path_param)) != ESP_OK) {
+        return send_error(req, "400 Bad Request", "missing path param");
+    }
+    const bool to_sd   = (strncmp(path_param, "sd/", 3) == 0);
+    const bool to_apps = (strncmp(path_param, "apps/", 5) == 0);
+    if ((!to_sd && !to_apps) || strstr(path_param, "..") ||
+        path_param[strlen(path_param) - 1] == '/') {
+        return send_error(req, "403 Forbidden", "path must be under apps/ or sd/");
+    }
+    char full[192];
+    if (to_sd) {
+        if (!sd_storage_ready()) {
+            return send_error(req, "503 Service Unavailable", "sd_not_mounted");
+        }
+        snprintf(full, sizeof(full), "/sdcard/%s", path_param + 3);
+    } else {
+        if (mount_storage_lazy() != ESP_OK) {
+            return send_error(req, "503 Service Unavailable", "storage_unavailable");
+        }
+        snprintf(full, sizeof(full), "/littlefs/%s", path_param);
+    }
+    if (unlink(full) != 0) {
+        return send_error(req, "404 Not Found", "remove failed");
+    }
+    ESP_LOGI(TAG, "file removed: %s", full);
+    char resp[192];
+    snprintf(resp, sizeof(resp), "{\"status\":\"ok\",\"removed\":\"%s\"}", path_param);
+    return send_json(req, "200 OK", resp);
+}
+
 void game_endpoint_get_scene(scene_binding_t *out) {
     if (!out) return;
     // Lock-free snapshot, same class as get_puzzle_status: written on the
@@ -1244,6 +1281,12 @@ esp_err_t game_endpoint_init(httpd_handle_t server) {
         .handler  = handle_file_post,
         .user_ctx = NULL,
     };
+    static const httpd_uri_t uri_file_delete = {
+        .uri      = "/game/file",
+        .method   = HTTP_DELETE,
+        .handler  = handle_file_delete,
+        .user_ctx = NULL,
+    };
     static const httpd_uri_t uri_espnow_cmd_post = {
         .uri      = "/game/espnow/cmd",
         .method   = HTTP_POST,
@@ -1326,6 +1369,10 @@ esp_err_t game_endpoint_init(httpd_handle_t server) {
     if (err != ESP_OK) {
         ESP_LOGW(TAG, "register POST /game/step: %s", esp_err_to_name(err));
     }
+    err = httpd_register_uri_handler(server, &uri_file_delete);
+    if (err != ESP_OK) {
+        ESP_LOGW(TAG, "register DELETE /game/file: %s", esp_err_to_name(err));
+    }
     err = httpd_register_uri_handler(server, &uri_file_post);
     if (err != ESP_OK) {
         ESP_LOGW(TAG, "register /game/file: %s", esp_err_to_name(err));

idf_zacus/components/ota_server/ota_server.c

@@ -310,9 +310,9 @@ esp_err_t ota_server_init(void) {
     // HTTP server config
     httpd_config_t config = HTTPD_DEFAULT_CONFIG();
     config.server_port     = OTA_SERVER_PORT;
-    config.max_uri_handlers = 22;   // ota + voice_hook + game (incl. /game/step,
-                                    // /game/puzzle_state, /game/file, relay,
-                                    // /game/gamebook)
+    config.max_uri_handlers = 24;   // ota + voice_hook + game (incl. /game/step,
+                                    // /game/puzzle_state, /game/file POST+DELETE,
+                                    // relay, /game/gamebook)
                                     // + headroom
     config.uri_match_fn    = httpd_uri_match_wildcard;
     config.stack_size      = 8192;