fix(plugins): install local plugins on packaged desktop

The plugin compiler spawned esbuild through app.asar, and the subprocess
imported the React client barrel. Point esbuild at the unpacked binary,
add a react-free @paseo/plugin/server entry, and pass a typed PluginTheme
so plugin UI follows the active theme on desktop and mobile.

packages/app/src/plugins/theme.test.ts

@@ -0,0 +1,18 @@
+import { describe, expect, it } from "vitest";
+import { lightTheme } from "@/styles/theme";
+import { toPluginTheme } from "./theme";
+
+describe("toPluginTheme", () => {
+  it("maps the app theme into the plugin color tokens", () => {
+    expect(toPluginTheme(lightTheme)).toEqual({
+      colors: {
+        surface0: lightTheme.colors.surface0,
+        foreground: lightTheme.colors.foreground,
+        foregroundMuted: lightTheme.colors.foregroundMuted,
+        accent: lightTheme.colors.accent,
+        accentForeground: lightTheme.colors.accentForeground,
+        statusDanger: lightTheme.colors.statusDanger,
+      },
+    });
+  });
+});