fix(FR-2853): restore copymonaco script lost during 26.4 main-merge

Resolves #FR-2853

The merge commit e5ea950 ("Merge branch 'main' into 26.4", 2026-04-24)
brought PR #6959 (FR-2697, self-host Monaco) into the 26.4 release branch
but, while resolving conflicts in package.json/electron-app/package.json/
index.html, both the `copymonaco` script definition and its invocation in
the `build` chain were silently dropped from root package.json.

As a result v26.4.6 and v26.4.7 ship a release zip with no
`resources/monaco/vs/` tree, and any UI that uses Monaco (VFolder file
editor, Theme JSON config modal) fails to load `/resources/monaco/vs/loader.js`
in deployed environments.

main is unaffected, which is why local builds reproduced fine and the
regression went unnoticed through two releases.

Restore the two lost lines in root package.json:
1. Re-insert `&& pnpm run copymonaco` between `copyconfig` and `tsc`
   in the `build` script.
2. Re-add the `copymonaco` script definition.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: yomybaby

package.json

@@ -19,7 +19,7 @@
     "vitest": "vitest run",
     "vitest:watch": "vitest",
     "wsproxy": "node ./src/wsproxy/local_proxy.js",
-    "build": "rm -rf build/web dist && mkdir -p build/web && pnpm run copyindex && pnpm run copyresource && pnpm run copyconfig && tsc && pnpm run -r --stream build",
+    "build": "rm -rf build/web dist && mkdir -p build/web && pnpm run copyindex && pnpm run copyresource && pnpm run copyconfig && pnpm run copymonaco && tsc && pnpm run -r --stream build",
     "build:react-only": "pnpm run --prefix ./react build:only",
     "server:p": "serve build/web",
     "dev": "node scripts/dev.mjs",
@@ -29,6 +29,7 @@
     "copyresource": "cp -Rp resources build/web && cp -Rp manifest build/web",
     "copyconfig": "./scripts/copy-config.js && cp version.json build/web && cp manifest.json build/web",
     "copyindex": "cp index.html build/web",
+    "copymonaco": "mkdir -p build/web/resources/monaco/vs && cp -R react/node_modules/monaco-editor/min/vs/. build/web/resources/monaco/vs/",
     "prepare": "husky",
     "theme-schema:update": "node scripts/gen-theme-schema.cjs"
   },