feat: add server settings (toggle on/off, port selection, start on system start) to Settings UI and backend

desktop/src/pubscript-desktop.c

@@ -157,6 +157,25 @@ int main(int argc, char *argv[]) {
   }
 
   int port = 18081;
+  char cfg_path[2048];
+  snprintf(cfg_path, sizeof(cfg_path), "%s/.config/pubscript/server.json", home);
+  FILE *cfg_fp = fopen(cfg_path, "r");
+  if (cfg_fp) {
+    char buf[1024];
+    size_t n = fread(buf, 1, sizeof(buf) - 1, cfg_fp);
+    buf[n] = '\0';
+    fclose(cfg_fp);
+    const char *port_key = strstr(buf, "\"port\"");
+    if (port_key) {
+      const char *colon = strchr(port_key, ':');
+      if (colon) {
+        int cfg_port = atoi(colon + 1);
+        if (cfg_port >= 1024 && cfg_port <= 65535) {
+          port = cfg_port;
+        }
+      }
+    }
+  }
   const char *env_port = getenv("PUBSCRIPT_DESKTOP_PORT");
   if (env_port && *env_port) {
     int p = atoi(env_port);