feat: scaffold matrix_client_pc (Wails + React-TS + mautrix-go + keyring)

Initial scaffold for issue 0147. App lives at
projects/element_agents/apps/matrix_client_pc/.

Deps:
- github.com/wailsapp/wails/v2 v2.11.0
- maunium.net/go/mautrix v0.25.2
- github.com/zalando/go-keyring v0.2.6

Next: MatrixService bindings + Login/Home React screens + helpers
(matrix_client_init, mas_oidc_loopback, keyring_token_store).

main.go

@@ -0,0 +1,36 @@
+package main
+
+import (
+	"embed"
+
+	"github.com/wailsapp/wails/v2"
+	"github.com/wailsapp/wails/v2/pkg/options"
+	"github.com/wailsapp/wails/v2/pkg/options/assetserver"
+)
+
+//go:embed all:frontend/dist
+var assets embed.FS
+
+func main() {
+	// Create an instance of the app structure
+	app := NewApp()
+
+	// Create application with options
+	err := wails.Run(&options.App{
+		Title:  "matrix_client_pc",
+		Width:  1024,
+		Height: 768,
+		AssetServer: &assetserver.Options{
+			Assets: assets,
+		},
+		BackgroundColour: &options.RGBA{R: 27, G: 38, B: 54, A: 1},
+		OnStartup:        app.startup,
+		Bind: []interface{}{
+			app,
+		},
+	})
+
+	if err != nil {
+		println("Error:", err.Error())
+	}
+}