Add Tauri app backend setup with dependencies and basic build script

- Introduced `build.rs` for Tauri build process initialization.
- Added `Cargo.toml` with dependencies for Tauri plugins, serialization, cryptography, and database handling.
- Generated `Cargo.lock` to lock package versions for consistency.

src-tauri/capabilities/default.json

@@ -0,0 +1,27 @@
+{
+  "$schema": "../gen/schemas/desktop-schema.json",
+  "identifier": "default",
+  "description": "Default capabilities for the main and login windows",
+  "windows": ["main", "login"],
+  "permissions": [
+    "core:default",
+    "core:window:allow-create",
+    "core:window:allow-close",
+    "core:window:allow-show",
+    "core:window:allow-hide",
+    "core:window:allow-set-focus",
+    "core:window:allow-center",
+    "core:webview:allow-create-webview-window",
+    "shell:allow-open",
+    "updater:default",
+    "process:allow-restart",
+    {
+      "identifier": "http:default",
+      "allow": [
+        { "url": "https://api.eritors.com/**" },
+        { "url": "https://scribe.eritors.com/**" },
+        { "url": "https://eritors.com/**" }
+      ]
+    }
+  ]
+}