feat(i18n): full app + docs localization (de/en)

- translate remaining pages/components (admin, analytics, redundancy,
  trash, compare, browse, watchlist, admin tools tab, category combobox,
  theme toggle, tool preview card, tool-new/edit) to t() calls
- locales: 453 keys each, parity verified
- docs: bilingual handbook + release notes via *.en.md variants,
  language-aware docs.tsx (markdown paths, nav titles, search index),
  LanguageSwitcher in docs header
- generate-docs: emit per-locale handbook/release/search output,
  localized index.json fields (fileEn/titleEn), en-aware snapshots

scripts/src/generate-docs.mjs

@@ -26,7 +26,12 @@ const releasesDir = resolve(root, "docs/releases");
 const targetDir = resolve(root, "artifacts/toolrate/public/docs");
 
 const isReleaseFile = (name) => /^v\d+\.\d+\.\d+\.md$/.test(name);
-const isHandbookFile = (name) => /\.md$/.test(name);
+const isEnReleaseFile = (name) => /^v\d+\.\d+\.\d+\.en\.md$/.test(name);
+const isHandbookFile = (name) => /\.md$/.test(name) && !name.endsWith(".en.md");
+const isEnHandbookFile = (name) => /\.en\.md$/.test(name);
+
+const enName = (file) => (file.endsWith(".md") ? `${file.slice(0, -3)}.en.md` : null);
+const deName = (file) => (file.endsWith(".en.md") ? `${file.slice(0, -6)}.md` : null);
 
 // ---------------------------------------------------------------------------
 // Version helpers
@@ -196,6 +201,15 @@ function slugify(name) {
   return name.replace(/\.md$/, "").toLowerCase().replace(/[^a-z0-9-]+/g, "-");
 }
 
+async function readFileOptional(path) {
+  try {
+    return await readFile(path, "utf8");
+  } catch (err) {
+    if (err.code === "ENOENT") return null;
+    throw err;
+  }
+}
+
 async function readHandbookPages() {
   let files;
   try {
@@ -208,12 +222,18 @@ async function readHandbookPages() {
   for (const file of files) {
     const content = await readFile(join(handbookDir, file), "utf8");
     const { frontmatter, body } = parseHandbook(content);
+    const enFile = enName(file);
+    const enContent = enFile ? await readFileOptional(join(handbookDir, enFile)) : null;
+    const en = enContent ? parseHandbook(enContent) : null;
     pages.push({
       slug: slugify(basename(file)),
       file,
       title: frontmatter.title ?? extractTitle(body) ?? basename(file),
       order: typeof frontmatter.order === "number" ? frontmatter.order : 999,
       body,
+      fileEn: en ? enFile : null,
+      titleEn: en ? en.frontmatter.title ?? extractTitle(en.body) ?? null : null,
+      bodyEn: en ? en.body : null,
     });
   }
   pages.sort((a, b) => a.order - b.order || a.title.localeCompare(b.title));
@@ -225,11 +245,12 @@ async function writeHandbookTo(dir) {
   await mkdir(dir, { recursive: true });
   for (const page of pages) {
     await writeFile(join(dir, page.file), page.body);
+    if (page.bodyEn) await writeFile(join(dir, page.fileEn), page.bodyEn);
   }
   await writeFile(
     join(dir, "index.json"),
     JSON.stringify(
-      pages.map(({ slug, file, title, order }) => ({ slug, file, title, order })),
+      pages.map(({ slug, file, title, order, fileEn, titleEn }) => ({ slug, file, title, order, fileEn, titleEn })),
       null,
       2,
     ),
@@ -256,6 +277,7 @@ function stripMarkdown(md) {
 
 async function buildSearchIndex(reference, handbookPages, releaseVersions) {
   const entries = [];
+  const entriesEn = [];
 
   for (const page of handbookPages) {
     const file = join(handbookDir, page.file);
@@ -267,44 +289,58 @@ async function buildSearchIndex(reference, handbookPages, releaseVersions) {
       kind: "guide",
       text: stripMarkdown(body),
     });
+    if (page.bodyEn) {
+      entriesEn.push({
+        title: page.titleEn ?? page.title,
+        href: `/docs/handbook/${page.slug}`,
+        kind: "guide",
+        text: stripMarkdown(page.bodyEn),
+      });
+    }
   }
 
   for (const tag of reference.tags) {
     for (const ep of tag.endpoints) {
-      entries.push({
+      const entry = {
         title: `${ep.method} ${ep.path}`,
         href: `/docs/reference/endpoints/${tag.name}#${ep.operationId}`,
         kind: "endpoint",
         text: `${ep.summary} ${ep.description} ${ep.parameters
           .map((p) => `${p.name} ${p.description}`)
           .join(" ")}`.trim(),
-      });
+      };
+      entries.push(entry);
+      entriesEn.push(entry);
     }
   }
 
   for (const schema of reference.schemas) {
     for (const field of schema.fields) {
-      entries.push({
+      const entry = {
         title: `${schema.name}.${field.name}`,
         href: `/docs/reference/schemas/${schema.name}#${field.name}`,
         kind: "field",
         text: `${field.description} ${field.constraints} ${field.type.value ?? ""}`.trim(),
-      });
+      };
+      entries.push(entry);
+      entriesEn.push(entry);
     }
   }
 
   for (const version of releaseVersions) {
     const file = join(releasesDir, `${version}.md`);
     const content = await readFile(file, "utf8");
-    entries.push({
+    const base = {
       title: version,
       href: `/docs/releases/${version}`,
       kind: "release",
-      text: stripMarkdown(content),
-    });
+    };
+    entries.push({ ...base, text: stripMarkdown(content) });
+    const enContent = await readFileOptional(join(releasesDir, `${version}.en.md`));
+    entriesEn.push({ ...base, text: stripMarkdown(enContent ?? content) });
   }
 
-  return entries;
+  return { entries, entriesEn };
 }
 
 // ---------------------------------------------------------------------------
@@ -348,7 +384,6 @@ async function main() {
     throw err;
   }
   releaseNames.sort(cmp).reverse();
-
   await rm(targetDir, { recursive: true, force: true });
   await mkdir(join(targetDir, "handbook"), { recursive: true });
   await mkdir(join(targetDir, "releases"), { recursive: true });
@@ -363,7 +398,18 @@ async function main() {
   const handbookPages = await buildHandbookIndex();
   await writeFile(
     join(targetDir, "handbook/index.json"),
-    JSON.stringify(handbookPages, null, 2),
+    JSON.stringify(
+      handbookPages.map(({ slug, file, title, order, fileEn, titleEn }) => ({
+        slug,
+        file,
+        title,
+        order,
+        fileEn,
+        titleEn,
+      })),
+      null,
+      2,
+    ),
   );
 
   // 3. Release notes + versioned docs snapshots (last 7 versions)
@@ -372,6 +418,9 @@ async function main() {
     const version = parseVersion(name);
     const content = await readFile(join(releasesDir, name), "utf8");
     await copyFile(join(releasesDir, name), join(targetDir, "releases", name));
+    const enName = `${version}.en.md`;
+    const enContent = await readFileOptional(join(releasesDir, enName));
+    if (enContent) await copyFile(join(releasesDir, enName), join(targetDir, "releases", enName));
     const snapDir = join(releasesDir, version);
     const hasReference = await stat(join(snapDir, "reference.json"))
       .then(() => true)
@@ -399,12 +448,20 @@ async function main() {
           join(snapDir, "handbook", page.file),
           join(targetDir, "versions", version, "handbook", page.file),
         );
+        if (page.fileEn) {
+          await copyFile(
+            join(snapDir, "handbook", page.fileEn),
+            join(targetDir, "versions", version, "handbook", page.fileEn),
+          );
+        }
       }
     }
     versions.push({
       version,
       file: `releases/${name}`,
+      fileEn: enContent ? `releases/${enName}` : null,
       title: extractTitle(content) ?? version,
+      titleEn: enContent ? extractTitle(enContent) ?? version : null,
       date: extractDate(content) ?? null,
       hasReference,
       hasHandbook,
@@ -414,12 +471,13 @@ async function main() {
   await writeFile(join(targetDir, "index.json"), JSON.stringify(versions, null, 2));
 
   // 4. Search index
-  const searchIndex = await buildSearchIndex(reference, handbookPages, versions.map((v) => v.version));
-  await writeFile(join(targetDir, "search.json"), JSON.stringify(searchIndex, null, 2));
+  const { entries, entriesEn } = await buildSearchIndex(reference, handbookPages, versions.map((v) => v.version));
+  await writeFile(join(targetDir, "search.json"), JSON.stringify(entries, null, 2));
+  await writeFile(join(targetDir, "search.en.json"), JSON.stringify(entriesEn, null, 2));
 
   console.log(
     `[generate-docs] synced ${versions.length} release(s), ${handbookPages.length} handbook page(s), ` +
-      `${reference.schemas.length} schema(s), ${searchIndex.length} search entries`,
+      `${reference.schemas.length} schema(s), ${entries.length} search entries`,
   );
 }