fix: resolve build — move main.go to root, fix Makefile wails path, update Wails to v2.12.0

- Moved main.go from cmd/app/ to project root (Wails convention)
- Makefile now resolves wails binary via GOPATH/bin fallback
- Updated wails/v2 dependency from v2.9.2 to v2.12.0
- Fixed preferences round-trip bug (store as single JSON blob)
- Fixed import strategy test (needs non-empty profile data)

frontend/wailsjs/runtime/package.json

@@ -0,0 +1,24 @@
+{
+  "name": "@wailsapp/runtime",
+  "version": "2.0.0",
+  "description": "Wails Javascript runtime library",
+  "main": "runtime.js",
+  "types": "runtime.d.ts",
+  "scripts": {
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/wailsapp/wails.git"
+  },
+  "keywords": [
+    "Wails",
+    "Javascript",
+    "Go"
+  ],
+  "author": "Lea Anthony <lea.anthony@gmail.com>",
+  "license": "MIT",
+  "bugs": {
+    "url": "https://github.com/wailsapp/wails/issues"
+  },
+  "homepage": "https://github.com/wailsapp/wails#readme"
+}