chore(i18n): refactor and cleanup (#805)

* checkpoint

* finish

* docs

quartz/plugins/emitters/contentIndex.ts

@@ -6,6 +6,7 @@ import { FilePath, FullSlug, SimpleSlug, joinSegments, simplifySlug } from "../.
 import { QuartzEmitterPlugin } from "../types"
 import { toHtml } from "hast-util-to-html"
 import { write } from "./helpers"
+import { i18n } from "../../i18n"
 
 export type ContentIndex = Map<FullSlug, ContentDetails>
 export type ContentDetails = {
@@ -38,7 +39,7 @@ function generateSiteMap(cfg: GlobalConfiguration, idx: ContentIndex): string {
   const base = cfg.baseUrl ?? ""
   const createURLEntry = (slug: SimpleSlug, content: ContentDetails): string => `<url>
     <loc>https://${joinSegments(base, encodeURI(slug))}</loc>
-    <lastmod>${content.date?.toISOString()}</lastmod>
+    ${content.date && `<lastmod>${content.date.toISOString()}</lastmod>`}
   </url>`
   const urls = Array.from(idx)
     .map(([slug, content]) => createURLEntry(simplifySlug(slug), content))
@@ -78,7 +79,7 @@ function generateRSSFeed(cfg: GlobalConfiguration, idx: ContentIndex, limit?: nu
     <channel>
       <title>${escapeHTML(cfg.pageTitle)}</title>
       <link>https://${base}</link>
-      <description>${!!limit ? `Last ${limit} notes` : "Recent notes"} on ${escapeHTML(
+      <description>${!!limit ? i18n(cfg.locale).pages.rss.lastFewNotes({ count: limit }) : i18n(cfg.locale).pages.rss.recentNotes} on ${escapeHTML(
         cfg.pageTitle,
       )}</description>
       <generator>Quartz -- quartz.jzhao.xyz</generator>