feat(search): add pagefind provider support

Add Pagefind indexing and browser search adapters behind a provider switch.

This lets prebuild generate either Stork or Pagefind search artifacts and lets the existing search UI run against Pagefind while preserving scoped filters, excerpts, and result metadata.

test/prebuild/pagefind.test.js

@@ -0,0 +1,64 @@
+import { describe, it, expect } from 'vitest'
+
+import {
+    mapSitemapEntryToPagefindRecord,
+    shouldIndexSitemapEntry
+} from '~/helpers/pagefind/index.js'
+
+describe('Pagefind records', () => {
+    it('should skip sitemap entries without searchable payloads', () => {
+        expect( shouldIndexSitemapEntry({
+            route: '/games',
+            payload: {}
+        }) ).toBe( false )
+    })
+
+    it('should map benchmark entries to Pagefind records', () => {
+        const record = mapSitemapEntryToPagefindRecord({
+            route: '/app/example/benchmarks',
+            payload: {
+                app: {
+                    name: 'Example App',
+                    text: '✅ Native support',
+                    content: 'Runs fast on Apple Silicon',
+                    aliases: [ 'Example' ],
+                    tags: [ 'Utilities' ],
+                    status: 'no-in-progress',
+                    slug: 'example',
+                    category: {
+                        slug: 'system-tools',
+                        label: 'System Tools'
+                    },
+                    lastUpdated: {
+                        timestamp: 1234567890
+                    }
+                }
+            }
+        })
+
+        expect( record ).toMatchObject({
+            url: '/app/example/benchmarks',
+            language: 'en',
+            meta: {
+                title: 'Example App Benchmarks',
+                text: '✅ Native support',
+                slug: 'example',
+                categorySlug: 'system-tools',
+                routeType: 'benchmarks',
+                lastUpdatedTimestamp: '1234567890'
+            },
+            filters: {
+                status: [ 'no_in_progress' ],
+                category: [ 'system_tools' ],
+                type: [ 'benchmarks' ]
+            },
+            sort: {
+                updated: '1234567890'
+            }
+        })
+
+        expect( record.content ).toContain('Example App Benchmarks')
+        expect( record.content ).toContain('Runs fast on Apple Silicon')
+        expect( record.content ).toContain('Apple Silicon App Tested')
+    })
+})