feat: add mpv sidecar IPC and Tauri commands

Persistent BufReader + request_id matching for correct event handling.
Audio-file passed during loadfile for frame-accurate sync.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

client/src-tauri/src/lib.rs

@@ -1,14 +1,27 @@
-// Learn more about Tauri commands at https://tauri.app/develop/calling-rust/
-#[tauri::command]
-fn greet(name: &str) -> String {
-    format!("Hello, {}! You've been greeted from Rust!", name)
-}
+mod mpv;
+mod commands;
+
+use commands::MpvState;
+use mpv::Mpv;
+use std::sync::Mutex;
 
 #[cfg_attr(mobile, tauri::mobile_entry_point)]
 pub fn run() {
     tauri::Builder::default()
         .plugin(tauri_plugin_opener::init())
-        .invoke_handler(tauri::generate_handler![greet])
+        .manage(MpvState(Mutex::new(Mpv::new())))
+        .invoke_handler(tauri::generate_handler![
+            commands::mpv_start,
+            commands::mpv_stop,
+            commands::mpv_load,
+            commands::mpv_seek,
+            commands::mpv_pause,
+            commands::mpv_resume,
+            commands::mpv_set_loop,
+            commands::mpv_clear_loop,
+            commands::mpv_time_pos,
+            commands::mpv_duration,
+        ])
         .run(tauri::generate_context!())
         .expect("error while running tauri application");
 }