refactor(metadata): centralize metadata generation with new templates and improved path handling

- Add generateStaticPageMetadata() for generic pages
- Improve path normalization in buildCanonicalUrl() and buildLanguageAlternates()
- Update all generators to use createPageMetadata() template
- Move FaqItem type definition to generated metadata file
- Fix canonical URL building to use alternates.canonical throughout

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: ericyangpan

scripts/generate/generate-metadata.mjs

@@ -389,10 +389,14 @@ function main() {
   const content = `${header}
 
 import type { CollectionSection } from '../collections'
-import type { FaqItem } from '../faq'
 import type { ArticleMetadata } from './articles'
 import type { DocSection } from './docs'
 
+export type FaqItem = {
+  title: string
+  content: string
+}
+
 export const articlesMetadata: Record<string, ArticleMetadata[]> = ${formatObject(articles)}
 
 export const docsMetadata: Record<string, DocSection[]> = ${formatObject(docs)}

src/lib/generated/metadata.ts

@@ -2,10 +2,14 @@
 // DO NOT EDIT MANUALLY
 
 import type { CollectionSection } from '../collections'
-import type { FaqItem } from '../faq'
 import type { ArticleMetadata } from './articles'
 import type { DocSection } from './docs'
 
+export type FaqItem = {
+  title: string
+  content: string
+}
+
 export const articlesMetadata: Record<string, ArticleMetadata[]> = {
   en: [
     {