feat: move remote desktop (RDP/VNC/Telnet) into a first-party plugin

Relocates guacamole backend/frontend source and tests into
plugins/remote-desktop, following the ssh-terminal/docker pattern.

plugins/remote-desktop/frontend/guacamole-meta-key.test.ts

@@ -0,0 +1,45 @@
+import { describe, expect, it } from "vitest";
+import { detectMetaKeyFamily, metaKeyLabels } from "./guacamole-meta-key.js";
+
+describe("guacamole toolbar meta key labels", () => {
+  it("keeps Windows labels for RDP regardless of the local device", () => {
+    expect(
+      detectMetaKeyFamily("rdp", {
+        platform: "MacIntel",
+        userAgent: "Macintosh; Intel Mac OS X",
+        userAgentDataPlatform: "macOS",
+      }),
+    ).toBe("win");
+  });
+
+  it("labels VNC with the local device's modifier instead of Windows", () => {
+    expect(
+      detectMetaKeyFamily("vnc", {
+        platform: "MacIntel",
+        userAgent: "Macintosh; Intel Mac OS X",
+        userAgentDataPlatform: "macOS",
+      }),
+    ).toBe("cmd");
+    expect(
+      detectMetaKeyFamily("vnc", {
+        platform: "Linux x86_64",
+        userAgent: "X11; Linux x86_64",
+        userAgentDataPlatform: "Linux",
+      }),
+    ).toBe("super");
+    expect(
+      detectMetaKeyFamily("vnc", {
+        platform: "Win32",
+        userAgent: "Windows NT 10.0",
+        userAgentDataPlatform: "Windows",
+      }),
+    ).toBe("win");
+  });
+
+  it("exposes Super/Cmd button copy for non-Windows VNC sessions", () => {
+    expect(metaKeyLabels("super").short).toBe("Super");
+    expect(metaKeyLabels("super").lock).toBe("Super+L");
+    expect(metaKeyLabels("cmd").short).toBe("Cmd");
+    expect(metaKeyLabels("cmd").lock).toBe("Cmd+L");
+  });
+});