Add timezone preference across time displays

src/routes/campaigns/+page.svelte

@@ -1,4 +1,5 @@
 <script lang="ts">
+    import { timeFormat } from '$ui/stores/time-zone.js';
     import { onMount } from 'svelte';
     import { page } from '$app/stores';
     import { goto } from '$app/navigation';
@@ -210,7 +211,7 @@
     let historyByDay = $derived.by(() => {
         const groups = new Map<string, Deployment[]>();
         for (const d of history.slice(0,limit)) {
-            const key = new Date(d.started_at).toDateString();
+            const key = $timeFormat.date(d.started_at);
             if (!groups.has(key)) groups.set(key, []);
             groups.get(key)!.push(d);
         }
@@ -283,7 +284,7 @@
 
             {#if driftOpen}
                 <div class="drift-body" id="drift-body">
-                    {#if drift}<p class="scan-context">Scanned {new Date(drift.scannedAt).toLocaleString()}. Selection controls the action scope; search only changes the visible list.</p>{/if}
+                    {#if drift}<p class="scan-context">Scanned {$timeFormat.dateTime(drift.scannedAt)}. Selection controls the action scope; search only changes the visible list.</p>{/if}
                     {#if drift && drift.totalDrift > 0}
                         <input
                             class="drift-filter" aria-label="Filter drift by server"
@@ -385,7 +386,7 @@
     {:else if plan}
         <p><strong>{reviewAll ? 'Entire fleet' : 'Selected servers'}: {plan.servers.length} server{plan.servers.length === 1 ? '' : 's'}, {plan.files.length} file change{plan.files.length === 1 ? '' : 's'}.</strong></p>
         <p>Files change immediately. Each affected server restarts after a fresh check confirms it is empty, then waits for health verification. Untracked files will be removed.</p>
-        <p class="scan-context">Reviewed {new Date(plan.scannedAt).toLocaleString()}. Changes to this plan require another review.</p>
+        <p class="scan-context">Reviewed {$timeFormat.dateTime(plan.scannedAt)}. Changes to this plan require another review.</p>
         <div class="plan-files">{#each plan.servers as server}{@const files = plan.files.filter(file => file.server === server)}{#if files.length}<section><h3><ServerIdentity name={server} /></h3>{#each files as file}<div class="plan-file"><strong>{file.driftKind === 'untracked' ? 'Remove' : file.driftKind === 'missing' ? 'Restore' : 'Replace'} <code>{file.relPath}</code></strong><span>{file.beforeSize === null ? 'Absent' : `${file.beforeSize} bytes`} → {file.afterSize === null ? 'Removed' : `${file.afterSize} bytes`}</span><details><summary>File fingerprints</summary><p>Before: {file.beforeSha256 ?? 'Absent'}<br />After: {file.afterSha256 ?? 'Removed'}</p></details></div>{/each}</section>{/if}{/each}</div>
     {/if}
     {#snippet actions()}<Button variant="ghost" disabled={running || reviewing} onclick={() => reviewOpen = false}>Cancel</Button><Button variant="danger" disabled={running || reviewing || !plan?.files.length} loading={running} onclick={runDrift}>Apply {plan?.files.length ?? 0} reviewed changes</Button>{/snippet}