[chore] Replace npx with pnpx across the codebase (#5329)

## Summary
- Migrated all `npx` commands to `pnpx` to align with the pnpm ecosystem
- Updated all occurrences across the codebase for consistency

## Changes
- **Package.json scripts**: Updated test:browser, preinstall, and
collect-i18n scripts
- **GitHub Actions workflows**: Updated all workflow files that use npx
(test-ui, i18n, update-manager-types, etc.)
- **Documentation**: Updated browser_tests/README.md and
docs/extensions/development.md
- **Husky pre-commit hook**: Updated lint-staged and tsx commands
- **MCP configuration**: Updated .mcp.json to use pnpx

## Test Plan
- [ ] CI tests pass
- [ ] Local development commands work with pnpx
- [ ] GitHub Actions workflows execute successfully

🤖 Generated with Claude Code

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-5329-chore-Replace-npx-with-pnpx-across-the-codebase-2646d73d36508127bd43d14b8364aeb1)
by [Unito](https://www.unito.io)

package.json

@@ -19,11 +19,11 @@
     "format:no-cache": "prettier --write './**/*.{js,ts,tsx,vue,mts}' --list-different",
     "format:check:no-cache": "prettier --check './**/*.{js,ts,tsx,vue,mts}'",
     "test:all": "nx run test",
-    "test:browser": "npx nx e2e",
+    "test:browser": "pnpm exec nx e2e",
     "test:component": "nx run test src/components/",
     "test:litegraph": "vitest run --config vitest.litegraph.config.ts",
     "test:unit": "nx run test tests-ui/tests",
-    "preinstall": "npx only-allow pnpm",
+    "preinstall": "pnpm dlx only-allow pnpm",
     "prepare": "husky || true && git config blame.ignoreRevsFile .git-blame-ignore-revs || true",
     "preview": "nx preview",
     "lint": "eslint src --cache",
@@ -35,7 +35,7 @@
     "knip": "knip --cache",
     "knip:no-cache": "knip",
     "locale": "lobe-i18n locale",
-    "collect-i18n": "npx playwright test --config=playwright.i18n.config.ts",
+    "collect-i18n": "pnpm exec playwright test --config=playwright.i18n.config.ts",
     "json-schema": "tsx scripts/generate-json-schema.ts",
     "storybook": "nx storybook -p 6006",
     "build-storybook": "storybook build"
@@ -158,4 +158,4 @@
     "zod": "^3.23.8",
     "zod-validation-error": "^3.3.0"
   }
-}
+}