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/plugin/src/server.test.ts

@@ -0,0 +1,57 @@
+import { existsSync, readFileSync } from "node:fs";
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+import { describe, expect, it } from "vitest";
+
+const srcDir = path.dirname(fileURLToPath(import.meta.url));
+const forbiddenSpecifiers = new Set([
+  "react",
+  "react/jsx-runtime",
+  "react-native",
+  "use-sync-external-store",
+  "use-sync-external-store/shim/with-selector",
+]);
+
+function localFile(fromFile: string, specifier: string): string {
+  const withoutJs = specifier.replace(/\.js$/, "");
+  for (const candidate of [`${withoutJs}.ts`, `${withoutJs}.tsx`, withoutJs]) {
+    const resolved = path.resolve(path.dirname(fromFile), candidate);
+    if (existsSync(resolved)) return resolved;
+  }
+  throw new Error(`Could not resolve ${specifier} from ${fromFile}`);
+}
+
+function valueImportSpecifiers(source: string): string[] {
+  const specifiers: string[] = [];
+  const pattern = /(?:^|\n)(?:export|import)\s+(?!type\b)(?:[\s\S]*?)from\s+["']([^"']+)["']/g;
+  for (const match of source.matchAll(pattern)) {
+    if (match[1]) specifiers.push(match[1]);
+  }
+  return specifiers;
+}
+
+function collectBareSpecifiers(entry: string): string[] {
+  const seen = new Set<string>();
+  const bare: string[] = [];
+  const queue = [entry];
+  while (queue.length > 0) {
+    const file = queue.pop();
+    if (!file || seen.has(file)) continue;
+    seen.add(file);
+    for (const specifier of valueImportSpecifiers(readFileSync(file, "utf8"))) {
+      if (specifier.startsWith(".")) {
+        queue.push(localFile(file, specifier));
+        continue;
+      }
+      bare.push(specifier);
+    }
+  }
+  return bare;
+}
+
+describe("@paseo/plugin/server", () => {
+  it("does not load react or the client hook graph", () => {
+    const specifiers = collectBareSpecifiers(path.join(srcDir, "server.ts"));
+    expect(specifiers.filter((specifier) => forbiddenSpecifiers.has(specifier))).toEqual([]);
+  });
+});