TutorialVault: complete Tauri v2 port with runtime fixes

Rename from TutorialDock to TutorialVault. Remove legacy Python app
and scripts. Fix video playback, subtitles, metadata display, window
state persistence, and auto-download of ffmpeg/ffprobe on first run.
Bundle fonts via npm instead of runtime download.

src-tauri/tauri.conf.json

@@ -1,8 +1,8 @@
 {
   "$schema": "https://raw.githubusercontent.com/tauri-apps/tauri/dev/crates/tauri-utils/schema.json",
-  "productName": "TutorialDock",
+  "productName": "TutorialVault",
   "version": "0.1.0",
-  "identifier": "com.tutorialdock.app",
+  "identifier": "com.tutorialvault.app",
   "build": {
     "devUrl": "http://localhost:1420",
     "frontendDist": "../dist",
@@ -12,7 +12,7 @@
   "app": {
     "windows": [
       {
-        "title": "TutorialDock",
+        "title": "TutorialVault",
         "width": 1320,
         "height": 860,
         "minWidth": 640,
@@ -20,7 +20,7 @@
       }
     ],
     "security": {
-      "csp": "default-src 'self'; media-src 'self' tutdock: asset: https://asset.localhost; font-src 'self' tutdock: asset: https://asset.localhost data:; style-src 'self' tutdock: asset: https://asset.localhost 'unsafe-inline'; img-src 'self' tutdock: asset: https://asset.localhost data:; script-src 'self'"
+      "csp": "default-src 'self'; media-src 'self' http://tutdock.localhost; font-src 'self' data:; style-src 'self' 'unsafe-inline'; img-src 'self' data:; script-src 'self'"
     }
   },
   "bundle": {
@@ -34,7 +34,5 @@
       "icons/icon.ico"
     ]
   },
-  "plugins": {
-    "dialog": {}
-  }
+  "plugins": {}
 }