feat(dialog): add file history dialog component

src/lib/components/FileHistoryDialog.svelte

@@ -0,0 +1,106 @@
+<script lang="ts">
+  import { AlertCircle, GitCompare, History, LoaderCircle, RotateCcw, X } from "@lucide/svelte";
+  import type { GitCommit } from "../types";
+
+  const commitDateFormatter = new Intl.DateTimeFormat(undefined, {
+    dateStyle: "medium",
+    timeStyle: "short",
+  });
+
+  interface Props {
+    fileHistory: GitCommit[];
+    filePath: string;
+    isBusy: boolean;
+    isLoading: boolean;
+    error?: string;
+    onDiff: (commit: GitCommit) => void;
+    onRestore: (commit: GitCommit) => void;
+    onClose: () => void;
+  }
+
+  let {
+    fileHistory = [],
+    filePath = "",
+    isBusy = false,
+    isLoading = false,
+    error = "",
+    onDiff = () => {},
+    onRestore = () => {},
+    onClose = () => {},
+  }: Props = $props();
+
+  function formatCommitDate(value: string): string {
+    const date = new Date(value);
+    if (Number.isNaN(date.getTime())) return value;
+    return commitDateFormatter.format(date);
+  }
+
+  function fileName(path: string): string {
+    return path.split(/[\\/]/).pop() ?? path;
+  }
+
+  function closeFromBackdrop(event: MouseEvent) {
+    if (event.target === event.currentTarget && !isBusy) onClose();
+  }
+</script>
+
+<div class="dialog-backdrop app-chrome-backdrop file-history-dialog-backdrop" role="presentation" onclick={closeFromBackdrop}>
+  <div class="file-history-dialog" role="dialog" aria-modal="true" aria-labelledby="file-history-dialog-title" tabindex="-1">
+    <header class="file-history-dialog-header">
+      <div class="file-history-dialog-icon" aria-hidden="true"><History size={19} /></div>
+      <div class="file-history-dialog-heading">
+        <span class="eyebrow">File history</span>
+        <h2 id="file-history-dialog-title">{fileName(filePath)}</h2>
+        <span class="file-history-dialog-path" title={filePath}>{filePath}</span>
+      </div>
+      <button class="dialog-icon-button" type="button" onclick={onClose} disabled={isBusy} aria-label="Close file history">
+        <X size={16} aria-hidden="true" />
+      </button>
+    </header>
+
+    <div class="file-history-dialog-body">
+      {#if isLoading}
+        <div class="file-history-dialog-state" role="status" aria-live="polite">
+          <LoaderCircle class="spin" size={22} aria-hidden="true" />
+          <strong>Loading file history…</strong>
+          <span>Reading commits that changed this file.</span>
+        </div>
+      {:else if error}
+        <div class="file-history-dialog-state error" role="alert">
+          <AlertCircle size={22} aria-hidden="true" />
+          <strong>File history could not be loaded.</strong>
+          <span>{error}</span>
+        </div>
+      {:else if fileHistory.length === 0}
+        <div class="file-history-dialog-state">
+          <History size={22} aria-hidden="true" />
+          <strong>No history found.</strong>
+          <span>This file has no committed changes yet.</span>
+        </div>
+      {:else}
+        <div class="file-history-dialog-list">
+          {#each fileHistory as item (item.hash)}
+            <article class="file-history-dialog-row">
+              <div class="file-history-dialog-commit">
+                <span class="commit-avatar" aria-hidden="true">{item.author_name.trim().slice(0, 2).toUpperCase() || "?"}</span>
+                <div>
+                  <strong title={item.summary}>{item.summary}</strong>
+                  <span><code>{item.short_hash}</code> · {item.author_name}</span>
+                </div>
+              </div>
+              <time datetime={item.date}>{formatCommitDate(item.date)}</time>
+              <div class="file-history-dialog-actions">
+                <button class="btn-sm" type="button" onclick={() => onDiff(item)} disabled={isBusy} title="Show changes against the working tree">
+                  <GitCompare size={14} aria-hidden="true" /> Diff
+                </button>
+                <button class="btn-sm" type="button" onclick={() => onRestore(item)} disabled={isBusy} title="Restore this file from the selected commit">
+                  <RotateCcw size={14} aria-hidden="true" /> Restore
+                </button>
+              </div>
+            </article>
+          {/each}
+        </div>
+      {/if}
+    </div>
+  </div>
+</div>