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)

main.go

@@ -0,0 +1,42 @@
+// Nexus Terminal – a desktop SSH, Telnet and RAW TCP client built with Wails v2.
+// This is the main entry point for the application.
+package main
+
+import (
+	"log"
+
+	"github.com/wailsapp/wails/v2"
+	"github.com/wailsapp/wails/v2/pkg/options"
+	"github.com/wailsapp/wails/v2/pkg/options/assetserver"
+
+	application "github.com/copilot-ssh-client/app/internal/app"
+	"github.com/copilot-ssh-client/app/frontend"
+)
+
+func main() {
+	nexus := application.NewApp()
+
+	// The API service is created during Startup once storage is initialised.
+	// We bind the App itself so Wails can call lifecycle hooks, and use
+	// OnStartup to wire everything, then bind the API service separately.
+	err := wails.Run(&options.App{
+		Title:     "Nexus Terminal",
+		Width:     1400,
+		Height:    900,
+		MinWidth:  1024,
+		MinHeight: 600,
+		AssetServer: &assetserver.Options{
+			Assets: frontend.Assets,
+		},
+		BackgroundColour: &options.RGBA{R: 26, G: 26, B: 46, A: 255}, // #1a1a2e
+		OnStartup:        nexus.Startup,
+		OnShutdown:       nexus.Shutdown,
+		OnDomReady:       nexus.DomReady,
+		Bind: []interface{}{
+			nexus.APIService(),
+		},
+	})
+	if err != nil {
+		log.Fatalf("failed to start Nexus Terminal: %v", err)
+	}
+}