Initial commit: FoFreeXit Phase 1 (Viewer) + Phase 2 (Annotate)

PDF viewer (render/search/text-select/thumbnails/outline) and annotation
engine (Highlight/Underline/Strikeout/Square/FreeText/Note) over PDFium +
lopdf, with Unicode font embedding for Vietnamese text and undo/redo.

app/src-tauri/tauri.conf.json

@@ -0,0 +1,33 @@
+{
+  "$schema": "https://schema.tauri.app/config/2",
+  "productName": "FoFreeXit",
+  "version": "0.1.0",
+  "identifier": "com.fofreexit.app",
+  "build": {
+    "frontendDist": "../src"
+  },
+  "app": {
+    "withGlobalTauri": true,
+    "windows": [
+      {
+        "label": "main",
+        "title": "FoFreeXit — PDF Viewer (Phase 1)",
+        "width": 1100,
+        "height": 850
+      }
+    ],
+    "security": {
+      "csp": null
+    }
+  },
+  "bundle": {
+    "active": true,
+    "targets": "all",
+    "icon": [
+      "icons/32x32.png",
+      "icons/128x128.png",
+      "icons/icon.ico",
+      "icons/icon.png"
+    ]
+  }
+}