🤖 fix: restore React DevTools by reverting to dynamic import (#707)

The refactor in a55417a changed from using dynamic import() inside 
app.whenReady() to using require() at module load time. This broke 
React DevTools because electron-devtools-installer accesses Electron 
APIs that aren't available until the app is ready.

Reverted to the working approach from commit 1e08943 that uses
await import() inside the app.whenReady() handler.

_Generated with `mux`_

Author: ammar-agent

docs/AGENTS.md

@@ -18,6 +18,7 @@ gh pr view <number> --json mergeable,mergeStateStatus | jq '.'
 ./scripts/wait_pr_checks.sh <pr_number>
 ```
 
+- Generally run `wait_pr_checks` after submitting a PR to ensure CI passes.
 - Status decoding: `mergeable=MERGEABLE` clean; `CONFLICTING` needs resolution. `mergeStateStatus=CLEAN` ready, `BLOCKED` waiting for CI, `BEHIND` rebase, `DIRTY` conflicts.
 - If behind: `git fetch origin && git rebase origin/main && git push --force-with-lease`.
 - Never enable auto-merge or merge at all unless the user explicitly says "merge it".

src/desktop/main.ts

@@ -25,33 +25,7 @@ import assert from "@/common/utils/assert";
 import { loadTokenizerModules } from "@/node/utils/main/tokenizer";
 
 // React DevTools for development profiling
-// Using require() instead of import since it's dev-only and conditionally loaded
-interface Extension {
-  name: string;
-  id: string;
-}
-
-type ExtensionInstaller = (
-  ext: { id: string },
-  options?: { loadExtensionOptions?: { allowFileAccess?: boolean } }
-) => Promise<Extension>;
-
-let installExtension: ExtensionInstaller | null = null;
-let REACT_DEVELOPER_TOOLS: { id: string } | null = null;
-
-if (!app.isPackaged) {
-  try {
-    // eslint-disable-next-line @typescript-eslint/no-require-imports
-    const devtools = require("electron-devtools-installer") as {
-      default: ExtensionInstaller;
-      REACT_DEVELOPER_TOOLS: { id: string };
-    };
-    installExtension = devtools.default;
-    REACT_DEVELOPER_TOOLS = devtools.REACT_DEVELOPER_TOOLS;
-  } catch (error) {
-    console.log("React DevTools not available:", error);
-  }
-}
+// Using dynamic import() to avoid loading electron-devtools-installer at module init time
 
 // IMPORTANT: Lazy-load heavy dependencies to maintain fast startup time
 //
@@ -509,8 +483,12 @@ if (gotTheLock) {
       migrateLegacyMuxHome();
 
       // Install React DevTools in development
-      if (!app.isPackaged && installExtension && REACT_DEVELOPER_TOOLS) {
+      if (!app.isPackaged) {
         try {
+          // eslint-disable-next-line no-restricted-syntax
+          const { default: installExtension, REACT_DEVELOPER_TOOLS } = await import(
+            "electron-devtools-installer"
+          );
           const extension = await installExtension(REACT_DEVELOPER_TOOLS, {
             loadExtensionOptions: { allowFileAccess: true },
           });