chore(wails): scaffold v3 project boilerplate

Wails v3 replaces the NPM-only dev entry point. This adds the Go module,
Taskfile, build metadata, and a minimal window shell without touching
frontend logic.

Co-authored-by: Cursor <cursoragent@cursor.com>

build/android/build.gradle

@@ -0,0 +1,4 @@
+// Top-level build file where you can add configuration options common to all sub-projects/modules.
+plugins {
+    id 'com.android.application' version '8.7.3' apply false
+}