refactor: migrate remaining Vue components to <script setup> (#38752)

Migrates the last four Options API components, so all 20 `.vue` files
now use `<script setup>`, and disables the Vue Options API runtime. This
will enable optimizations like Vue Vapor mode in the future.

Bug fixes done while migrating and testing:

- Branch selector: arrowing onto "Create branch …" threw a `TypeError`,
and Enter on it did nothing
- Dashboard: the search term was not escaped, so `&` injected query
parameters and `#` truncated the request
- Dashboard: an unknown `repo-search-filter` threw, and names like
`constructor` leaked `Object.prototype` members into the request
- Dashboard: an unknown archived/private filter rendered `function
Object() { [native code] }` as a checkbox tooltip
- Dashboard: removed a dropdown init that always ran against a
not-yet-rendered element
- Branch selector: the `document.body` click listener was never removed
on unmount
- Contributors: the chart plugin relied on an undeclared chart.js field
- Contributors: `contributorsStats` was mutated behind a `shallowRef`,
so future readers would not update
- Removed template attributes and pageData keys that no component had
read for years

---------

Signed-off-by: silverwind <me@silverwind.io>

tools/shared.ts

@@ -0,0 +1,32 @@
+import vuePlugin from '@vitejs/plugin-vue';
+import {stringPlugin} from 'vite-string-plugin';
+import type {Plugin} from 'vite';
+
+// custom elements, vue must render these as-is instead of resolving them as components
+const webComponents = new Set([
+  // our own, in web_src/js/webcomponents
+  'overflow-menu',
+  'relative-time',
+  // from dependencies
+  'markdown-toolbar',
+  'text-expander',
+]);
+
+export const vueDefines = {
+  __VUE_OPTIONS_API__: false,
+  __VUE_PROD_DEVTOOLS__: false,
+  __VUE_PROD_HYDRATION_MISMATCH_DETAILS__: false,
+};
+
+export function sharedPlugins(): Plugin[] {
+  return [
+    stringPlugin(),
+    vuePlugin({
+      template: {
+        compilerOptions: {
+          isCustomElement: (tag) => webComponents.has(tag),
+        },
+      },
+    }),
+  ];
+}