feat(compare): add German localization and revamp compare UI

Pass the application language into compare dialogs and add German
translations so titles, buttons and helper text render appropriately.
Refactor dialog markup to introduce a compact header with a GitCompare
icon, show changed-file counts, and surface contextual help and warnings.
Adjust and extend CSS for spacing, layout and responsive behavior.

- Pass app language into compare components and derive isGerman flag
- Replace icons and restructure headers; add counts, help and warnings
- Update styles for sizing, spacing, responsive rules and new classes

src/lib/components/CompareDialog.svelte

@@ -1,5 +1,5 @@
 <script lang="ts">
-  import { ArrowRight, FileCode, RotateCcw, X } from "@lucide/svelte";
+  import { ArrowRight, FileCode, GitCompare, RotateCcw, X } from "@lucide/svelte";
   import type { GitCommitComparison, GitDiffFile, FileStatusKind } from "../types";
 
   type SplitRow =
@@ -25,6 +25,7 @@
     restoreLabel?: string;
     /** When opened from a search hit, the term to highlight on matching lines. */
     highlightQuery?: string;
+    language?: "en" | "de";
     onClose: () => void;
     onRestore?: () => void;
     onSelectFile: (file: GitDiffFile) => void;
@@ -38,11 +39,14 @@
     toLabel = "",
     restoreLabel = "",
     highlightQuery = "",
+    language = "en",
     onClose = () => {},
     onRestore = undefined,
     onSelectFile = () => {},
   }: Props = $props();
 
+  let isGerman = $derived(language === "de");
+
   // Needle = first non-empty line of the search query, lowercased for matching.
   let highlightNeedle = $derived(
     highlightQuery
@@ -225,14 +229,17 @@
 >
   <div class="dialog compare-dialog" role="dialog" aria-modal="true" aria-label="Branch or commit comparison" tabindex="-1">
 
-    <header class="dialog-header">
-      <div>
-        <span class="eyebrow">Compare</span>
-        <h2 class="dialog-range">
-          <span class="hash" title={comparison.from_hash}>{fromLabel || comparison.from_short}</span>
-          <ArrowRight size={14} aria-hidden="true" />
-          <span class="hash" title={comparison.to_hash}>{toLabel || comparison.to_short}</span>
-        </h2>
+    <header class="compare-dialog-head">
+      <div class="compare-dialog-title">
+        <span class="compare-dialog-mark"><GitCompare size={18} aria-hidden="true" /></span>
+        <div>
+          <h2>{isGerman ? "Änderungen vergleichen" : "Compare changes"}</h2>
+          <p class="dialog-range">
+            <span class="hash" title={comparison.from_hash}>{fromLabel || comparison.from_short}</span>
+            <ArrowRight size={14} aria-hidden="true" />
+            <span class="hash" title={comparison.to_hash}>{toLabel || comparison.to_short}</span>
+          </p>
+        </div>
       </div>
       <div class="dialog-header-actions">
         {#if restoreLabel && onRestore}
@@ -241,19 +248,23 @@
             <span>{restoreLabel}</span>
           </button>
         {/if}
-        <button class="dialog-close" type="button" onclick={onClose} title="Close">
+        <button class="dialog-close" type="button" onclick={onClose} title={isGerman ? "Schließen" : "Close"} aria-label={isGerman ? "Vergleich schließen" : "Close comparison"}>
           <X size={18} aria-hidden="true" />
         </button>
       </div>
     </header>
 
     {#if comparison.files.length === 0}
-      <div class="blank-state">No differences — these versions are identical.</div>
+      <div class="blank-state">{isGerman ? "Keine Unterschiede - diese Versionen sind identisch." : "No differences - these versions are identical."}</div>
     {:else}
       <div class="dialog-body">
 
         <!-- File list -->
-        <aside class="dialog-files" aria-label="Changed files">
+        <aside class="dialog-files" aria-label={isGerman ? "Geänderte Dateien" : "Changed files"}>
+          <div class="compare-files-head">
+            <span>{isGerman ? "Geänderte Dateien" : "Changed files"}</span>
+            <strong>{comparison.files.length}</strong>
+          </div>
           {#each comparison.files as file (`${file.old_path ?? ""}:${file.path}`)}
             <button
               class="dialog-file-row"
@@ -275,9 +286,9 @@
         <!-- Diff pane -->
         <div class="dialog-diff">
           {#if !selectedFile}
-            <div class="blank-state">Select a file to see its changes.</div>
+            <div class="blank-state">{isGerman ? "Wähle eine Datei aus, um ihre Änderungen zu sehen." : "Select a file to see its changes."}</div>
           {:else if splitRows.length === 0}
-            <div class="blank-state">No textual changes for this file.</div>
+            <div class="blank-state">{isGerman ? "Keine textuellen Änderungen für diese Datei." : "No textual changes for this file."}</div>
           {:else}
             <!-- Path bar -->
             <div class="diff-header">
@@ -292,11 +303,11 @@
             <!-- Column headers -->
             <div class="split-col-headers">
               <div class="split-col-label">
-                <span>Before</span>
+                <span>{isGerman ? "Vorher" : "Before"}</span>
                 <span class="split-col-hash" title={comparison.from_hash}>{fromLabel || comparison.from_short}</span>
               </div>
               <div class="split-col-label">
-                <span>After</span>
+                <span>{isGerman ? "Nachher" : "After"}</span>
                 <span class="split-col-hash" title={comparison.to_hash}>{toLabel || comparison.to_short}</span>
               </div>
             </div>