hscontrol: remove the proto, gRPC and grpc-gateway stack

With the v1 API served by Huma and the CLI on the HTTP client, nothing
uses the gRPC service or its generated code. Delete proto/, the generated
gen/go and gen/openapiv2, grpcv1.go, the buf config, the proto .Proto()
helpers and gRPC config, and the proto build tooling from the flake and
CI.

cmd/dev/main.go

@@ -28,17 +28,14 @@ var errHealthTimeout = errors.New("health check timed out")
 
 var errEmptyAuthKey = errors.New("empty auth key in response")
 
-// maxDevPort is the highest --port value that keeps both the derived
-// metrics port (port+1010) and gRPC port (port+42363) inside the valid
-// 1..65535 TCP range.
-const maxDevPort = 23172
+// maxDevPort is the highest --port value that keeps the derived metrics
+// port (port+1010) inside the valid 1..65535 TCP range.
+const maxDevPort = 64525
 
 const devConfig = `---
 server_url: http://127.0.0.1:%d
 listen_addr: 127.0.0.1:%d
 metrics_listen_addr: 127.0.0.1:%d
-grpc_listen_addr: 127.0.0.1:%d
-grpc_allow_insecure: true
 
 noise:
   private_key_path: %s/noise_private.key
@@ -83,7 +80,7 @@ func main() {
 
 	if *port < 1 || *port > maxDevPort {
 		log.Fatalf(
-			"--port must be in 1..%d (higher values overflow the derived gRPC port); got %d",
+			"--port must be in 1..%d (higher values overflow the derived metrics port); got %d",
 			maxDevPort, *port,
 		)
 	}
@@ -101,7 +98,6 @@ func main() {
 
 func run() error {
 	metricsPort := *port + 1010 // default 9090
-	grpcPort := *port + 42363   // default 50443
 
 	tmpDir, err := os.MkdirTemp("", "headscale-dev-")
 	if err != nil {
@@ -114,8 +110,9 @@ func run() error {
 
 	// Write config.
 	configPath := filepath.Join(tmpDir, "config.yaml")
-	configContent := fmt.Sprintf(devConfig,
-		*port, *port, metricsPort, grpcPort,
+	configContent := fmt.Sprintf(
+		devConfig,
+		*port, *port, metricsPort,
 		tmpDir, tmpDir, tmpDir,
 	)
 
@@ -193,7 +190,8 @@ func run() error {
 	}
 
 	// Print banner.
-	fmt.Printf(`
+	fmt.Printf(
+		`
 === Headscale Dev Environment ===
   Server:  http://127.0.0.1:%d
   Metrics: http://127.0.0.1:%d