i18n: internationalize all admin pages

Add full i18n coverage for the admin section — locale keys, layout nav,
users, videos, and articles pages (list, new, edit).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/frontend/src/routes/admin/articles/[id]/+page.svelte

@@ -1,6 +1,7 @@
 <script lang="ts">
   import { goto } from "$app/navigation";
   import { toast } from "svelte-sonner";
+  import { _ } from "svelte-i18n";
   import { updateArticle, uploadFile } from "$lib/services";
   import { marked } from "marked";
   import { Button } from "$lib/components/ui/button";
@@ -40,9 +41,9 @@
     try {
       const res = await uploadFile(fd);
       imageId = res.id;
-      toast.success("Image uploaded");
+      toast.success($_("admin.common.image_uploaded"));
     } catch {
-      toast.error("Image upload failed");
+      toast.error($_("admin.common.image_upload_failed"));
     }
   }
 
@@ -62,10 +63,10 @@
         featured,
         publishDate: publishDate || undefined,
       });
-      toast.success("Article updated");
+      toast.success($_("admin.article_form.update_success"));
       goto("/admin/articles");
     } catch (e: any) {
-      toast.error(e?.message ?? "Failed to update article");
+      toast.error(e?.message ?? $_("admin.article_form.update_error"));
     } finally {
       saving = false;
     }
@@ -75,43 +76,43 @@
 <div class="p-3 sm:p-6">
   <div class="flex items-center gap-4 mb-6">
     <Button variant="ghost" href="/admin/articles" size="sm">
-      <span class="icon-[ri--arrow-left-line] h-4 w-4 mr-1"></span>Back
+      <span class="icon-[ri--arrow-left-line] h-4 w-4 mr-1"></span>{$_("common.back")}
     </Button>
-    <h1 class="text-2xl font-bold">Edit article</h1>
+    <h1 class="text-2xl font-bold">{$_("admin.article_form.edit_title")}</h1>
   </div>
 
   <div class="space-y-5 max-w-4xl">
     <div class="grid grid-cols-1 sm:grid-cols-2 gap-4">
       <div class="space-y-1.5">
-        <Label for="title">Title *</Label>
+        <Label for="title">{$_("admin.common.title_field")}</Label>
         <Input id="title" bind:value={title} />
       </div>
       <div class="space-y-1.5">
-        <Label for="slug">Slug *</Label>
+        <Label for="slug">{$_("admin.common.slug_field")}</Label>
         <Input id="slug" bind:value={slug} />
       </div>
     </div>
 
     <div class="space-y-1.5">
-      <Label for="excerpt">Excerpt</Label>
+      <Label for="excerpt">{$_("admin.article_form.excerpt")}</Label>
       <Textarea id="excerpt" bind:value={excerpt} rows={2} />
     </div>
 
     <!-- Markdown editor with live preview -->
     <div class="space-y-1.5">
       <div class="flex items-center justify-between">
-        <Label>Content (Markdown)</Label>
+        <Label>{$_("admin.article_form.content")}</Label>
         <div class="flex rounded-lg border border-border/40 overflow-hidden text-xs sm:hidden">
           <button
             type="button"
             class={`px-3 py-1 transition-colors ${editorTab === "write" ? "bg-primary/10 text-primary" : "text-muted-foreground"}`}
             onclick={() => (editorTab = "write")}
-          >Write</button>
+          >{$_("admin.common.write")}</button>
           <button
             type="button"
             class={`px-3 py-1 transition-colors ${editorTab === "preview" ? "bg-primary/10 text-primary" : "text-muted-foreground"}`}
             onclick={() => (editorTab = "preview")}
-          >Preview</button>
+          >{$_("admin.common.preview")}</button>
         </div>
       </div>
       <div class="sm:grid sm:grid-cols-2 sm:gap-4 min-h-96">
@@ -125,14 +126,14 @@
           {#if preview}
             {@html preview}
           {:else}
-            <p class="text-muted-foreground italic text-sm">Preview will appear here…</p>
+            <p class="text-muted-foreground italic text-sm">{$_("admin.article_form.preview_placeholder")}</p>
           {/if}
         </div>
       </div>
     </div>
 
     <div class="space-y-1.5">
-      <Label>Cover image</Label>
+      <Label>{$_("admin.common.cover_image")}</Label>
       {#if imageId}
         <img
           src={getAssetUrl(imageId, "thumbnail")}
@@ -145,7 +146,7 @@
 
     <!-- Author -->
     <div class="space-y-1.5">
-      <Label>Author</Label>
+      <Label>{$_("admin.article_form.author")}</Label>
       <Select type="single" bind:value={authorId}>
         <SelectTrigger class="w-full">
           {#if selectedAuthor}
@@ -154,11 +155,11 @@
             {/if}
             {selectedAuthor.artist_name}
           {:else}
-            <span class="text-muted-foreground">No author</span>
+            <span class="text-muted-foreground">{$_("admin.article_form.no_author")}</span>
           {/if}
         </SelectTrigger>
         <SelectContent>
-          <SelectItem value="">No author</SelectItem>
+          <SelectItem value="">{$_("admin.article_form.no_author")}</SelectItem>
           {#each data.authors as author (author.id)}
             <SelectItem value={author.id}>
               {#if author.avatar}
@@ -173,30 +174,30 @@
 
     <div class="grid grid-cols-1 sm:grid-cols-2 gap-4">
       <div class="space-y-1.5">
-        <Label for="category">Category</Label>
+        <Label for="category">{$_("admin.article_form.category")}</Label>
         <Input id="category" bind:value={category} />
       </div>
       <div class="space-y-1.5">
-        <Label for="publishDate">Publish date</Label>
+        <Label for="publishDate">{$_("admin.common.publish_date")}</Label>
         <Input id="publishDate" type="datetime-local" bind:value={publishDate} />
       </div>
     </div>
 
     <div class="space-y-1.5">
-      <Label>Tags</Label>
+      <Label>{$_("admin.common.tags")}</Label>
       <TagsInput bind:value={tags} />
     </div>
 
     <label class="flex items-center gap-2 cursor-pointer">
       <input type="checkbox" bind:checked={featured} class="rounded" />
-      <span class="text-sm">Featured</span>
+      <span class="text-sm">{$_("admin.common.featured")}</span>
     </label>
 
     <div class="flex gap-3 pt-2">
       <Button onclick={handleSubmit} disabled={saving}>
-        {saving ? "Saving…" : "Save changes"}
+        {saving ? $_("admin.common.saving") : $_("admin.common.save_changes")}
       </Button>
-      <Button variant="outline" href="/admin/articles">Cancel</Button>
+      <Button variant="outline" href="/admin/articles">{$_("common.cancel")}</Button>
     </div>
   </div>
 </div>