refactor(status): Support batch and all changes discard functionality

The file discarding mechanism has been significantly refactored to improve handling of multi-file operations. Instead of processing discards on a per-file basis, the system now supports batch actions for selected files or reverting all tracked modifications simultaneously. This update centralizes complex discard logic into dedicated functions across the component suite.

- Updated state management and types to handle arrays of file changes.
- Added UI elements and handlers for discarding all staged/unstaged changes.
- Enhanced the confirmation dialog to display multiple discarded targets in a list view.

src/lib/components/DiscardConfirmDialog.svelte

@@ -3,8 +3,8 @@
   import type { GitFileStatus } from "../types";
 
   interface Props {
-    file: GitFileStatus;
-    staged: boolean;
+    files: GitFileStatus[];
+    staged: boolean | null;
     scope: "file" | "hunk";
     isBusy: boolean;
     onConfirm: () => void | Promise<void>;
@@ -12,7 +12,7 @@
   }
 
   let {
-    file,
+    files,
     staged = false,
     scope = "file",
     isBusy = false,
@@ -20,10 +20,16 @@
     onClose = () => {},
   }: Props = $props();
 
-  let targetPath = $derived(file.old_path ? `${file.old_path} -> ${file.path}` : file.path);
-  let title = $derived(scope === "hunk" ? "Discard hunk?" : "Discard file changes?");
-  let scopeLabel = $derived(scope === "hunk" ? "Selected hunk" : "File changes");
-  let sourceLabel = $derived(staged ? "staged changes" : "unstaged changes");
+  function targetPath(file: GitFileStatus): string {
+    return file.old_path ? `${file.old_path} -> ${file.path}` : file.path;
+  }
+
+  let count = $derived(files.length);
+  let title = $derived(
+    scope === "hunk" ? "Discard hunk?" : count > 1 ? `Discard changes in ${count} files?` : "Discard file changes?"
+  );
+  let scopeLabel = $derived(scope === "hunk" ? "selected hunk" : count > 1 ? `${count} files` : "file");
+  let sourceLabel = $derived(staged === null ? "staged and unstaged changes" : staged ? "staged changes" : "unstaged changes");
 
 </script>
 
@@ -46,11 +52,22 @@
 
       <div class="discard-confirm-copy">
         <p>
-          This will reset the {sourceLabel} for the {scopeLabel.toLowerCase()} below.
+          This will reset the {sourceLabel} for the {scopeLabel} below.
         </p>
-        <code class="discard-target" title={targetPath}>{targetPath}</code>
+        {#if count > 1}
+          <ul class="discard-target-list">
+            {#each files.slice(0, 8) as file (`${file.old_path ?? ""}:${file.path}`)}
+              <li><code class="discard-target" title={targetPath(file)}>{targetPath(file)}</code></li>
+            {/each}
+            {#if files.length > 8}
+              <li class="discard-target-more">+{files.length - 8} more</li>
+            {/if}
+          </ul>
+        {:else if count === 1}
+          <code class="discard-target" title={targetPath(files[0])}>{targetPath(files[0])}</code>
+        {/if}
         <p class="discard-warning-text">
-          This cannot be undone. If the file only exists in your working tree, it can be deleted entirely.
+          This cannot be undone. If a file only exists in your working tree, it can be deleted entirely.
         </p>
       </div>
     </div>