feat: Maestro driver integration + DeviceDriver architecture (#32)

* proto(driver): drop launcher_activity from LaunchRequest

* refactor(driver): rename Driver to DeviceDriver, drop launcherActivity from Launch

* refactor(driver): rename package maestro to sidecar

* feat(driver): add ChromeDriver backed by chromedp

* feat(hierarchy): replace XML parser with TreeNode JSON parser

* refactor(driver): update mock and runner to DeviceDriver, drop launcherActivity

* feat(runner): add platform routing for web vs sidecar

* test(verifier): update hierarchy fixtures from XML to TreeNode JSON

* feat(sidecar): extract readLogcat/readProcMetrics; add MaestroDriverBackend

- Extract readLogcat() and readProcMetrics() as internal package-level
  helpers parameterised by serial
- Add MaestroDriverBackend wiring maestro-client AndroidDriver
- Drop launcherActivity from DriverBackend interface and StubDriverBackend
- Add maestro-utils and micrometer-core as explicit compile deps

* refactor(sidecar): inject DriverBackend into DriverService; drop launcherActivity

- Remove serial and default backend from DriverService constructor
- Make backend a required parameter
- Drop launcherActivity from launch RPC handler
- Create MaestroDriverBackend in Main.kt when platform is android

* test(sidecar): update tests for dropped launcherActivity and required backend

* chore(sidecar): remove unnecessary micrometer-core direct dependency

internal/hierarchy/hierarchy_test.go

@@ -2,14 +2,30 @@ package hierarchy
 
 import "testing"
 
-const sampleDump = `<?xml version='1.0' encoding='UTF-8' standalone='yes' ?>
-<hierarchy rotation="0">
-  <node class="android.widget.LinearLayout" package="app" bounds="[0,0][1080,2340]">
-    <node resource-id="app:id/title" text="Hello" bounds="[10,20][200,60]" clickable="false" enabled="true"/>
-    <node resource-id="app:id/row" text="Alice" content-desc="row" bounds="[0,100][1080,200]" clickable="true" enabled="true"/>
-    <node resource-id="app:id/row" text="Bob" content-desc="row" bounds="[0,200][1080,300]" clickable="true" enabled="true"/>
-  </node>
-</hierarchy>`
+// sampleDump is a Maestro TreeNode JSON equivalent of the old XML fixture.
+const sampleDump = `{
+  "attributes": {"class": "android.widget.LinearLayout", "package": "app", "bounds": "[0,0,1080,2340]"},
+  "children": [
+    {
+      "attributes": {"resource-id": "app:id/title", "text": "Hello", "bounds": "[10,20,200,60]"},
+      "children": [],
+      "clickable": false,
+      "enabled": true
+    },
+    {
+      "attributes": {"resource-id": "app:id/row", "text": "Alice", "content-desc": "row", "bounds": "[0,100,1080,200]"},
+      "children": [],
+      "clickable": true,
+      "enabled": true
+    },
+    {
+      "attributes": {"resource-id": "app:id/row", "text": "Bob", "content-desc": "row", "bounds": "[0,200,1080,300]"},
+      "children": [],
+      "clickable": true,
+      "enabled": true
+    }
+  ]
+}`
 
 func TestParseCountsNodes(t *testing.T) {
 	tree, err := Parse(sampleDump)
@@ -75,14 +91,76 @@ func TestUnknownSelector(t *testing.T) {
 }
 
 func TestDescPrefix(t *testing.T) {
-	xml := `<hierarchy>
-		<node content-desc="customer_row_abc-123" bounds="[0,0][100,100]"/>
-		<node content-desc="customer_row_def-456" bounds="[0,100][100,200]"/>
-		<node content-desc="supplier_row_xyz" bounds="[0,200][100,300]"/>
-	</hierarchy>`
-	tree, _ := Parse(xml)
+	input := `{
+	  "attributes": {},
+	  "children": [
+	    {"attributes": {"content-desc": "customer_row_abc-123", "bounds": "[0,0,100,100]"}, "children": []},
+	    {"attributes": {"content-desc": "customer_row_def-456", "bounds": "[0,100,100,200]"}, "children": []},
+	    {"attributes": {"content-desc": "supplier_row_xyz", "bounds": "[0,200,100,300]"}, "children": []}
+	  ]
+	}`
+	tree, _ := Parse(input)
 	rows := tree.FindAll("descPrefix:customer_row_")
 	if len(rows) != 2 {
 		t.Fatalf("want 2 customer rows, got %d", len(rows))
 	}
 }
+
+func TestBoolFieldsFromNode(t *testing.T) {
+	input := `{
+	  "attributes": {"resource-id": "x", "bounds": "[0,0,100,100]"},
+	  "children": [],
+	  "clickable": true,
+	  "enabled": false,
+	  "focused": true,
+	  "checked": true,
+	  "selected": false
+	}`
+	tree, err := Parse(input)
+	if err != nil {
+		t.Fatalf("Parse: %v", err)
+	}
+	if len(tree.Elements) != 1 {
+		t.Fatalf("want 1 element, got %d", len(tree.Elements))
+	}
+	el := tree.Elements[0]
+	if !el.Clickable {
+		t.Error("expected clickable=true")
+	}
+	if el.Enabled {
+		t.Error("expected enabled=false")
+	}
+	if !el.Focused {
+		t.Error("expected focused=true")
+	}
+	if !el.Checked {
+		t.Error("expected checked=true")
+	}
+	if el.Selected {
+		t.Error("expected selected=false")
+	}
+}
+
+func TestIdentifierFallback(t *testing.T) {
+	input := `{
+	  "attributes": {"identifier": "my-button", "bounds": "[0,0,100,100]"},
+	  "children": []
+	}`
+	tree, _ := Parse(input)
+	el := tree.Find("id:my-button")
+	if el == nil {
+		t.Fatal("expected match via identifier fallback")
+	}
+}
+
+func TestAccessibilityTextFallback(t *testing.T) {
+	input := `{
+	  "attributes": {"accessibilityText": "Close dialog", "bounds": "[0,0,50,50]"},
+	  "children": []
+	}`
+	tree, _ := Parse(input)
+	el := tree.Find("desc:Close dialog")
+	if el == nil {
+		t.Fatal("expected match via accessibilityText fallback")
+	}
+}