feat: typed script parameters with validation and icon-grid selector

- Add ScriptParameterConfig model (string, integer, float, boolean, select types)
- Server-side validation at both define-time and execute-time
- Parameters passed as SCRIPT_PARAM_* environment variables
- Web UI parameter editor in script create/edit dialog (add/remove/reorder)
- Icon-grid selector component (ported from wled-screen-controller)
- Replace audio device dropdown with icon-grid selector
- Replace callback event dropdown with icon-grid selector
- Localization for parameter UI (en, ru)

media_server/static/locales/en.json

@@ -74,6 +74,15 @@
   "scripts.execution.error_output": "Error Output",
   "scripts.execution.close": "Close",
   "scripts.confirm.unsaved": "You have unsaved changes. Are you sure you want to discard them?",
+  "scripts.field.parameters": "Parameters",
+  "scripts.params.add": "+ Add",
+  "scripts.params.remove": "Remove parameter",
+  "scripts.params.required": "Required",
+  "scripts.params.name_placeholder": "param_name",
+  "scripts.params.description_placeholder": "Parameter description",
+  "scripts.params.default_placeholder": "Default",
+  "scripts.params.options_placeholder": "option1, option2, ...",
+  "scripts.params.execute": "Execute",
   "callbacks.management": "Callback Management",
   "callbacks.description": "Callbacks are scripts triggered automatically by media control events (play, pause, stop, etc.)",
   "callbacks.add": "Add",