feat(serve): debounced site rebuild — burst uploads trigger one build, not N

Replace per-upload Astro build threads with a single background worker
(_site_rebuild_worker) that waits on an event, sleeps 60 s to let upload
bursts settle, then runs one full build + rsync. 271 concurrent uploads now
produce one build instead of 271 serialised builds, eliminating the OOM kill.
--webroot is re-enabled; merge-only path still runs immediately per upload.

Also: date filter row added to ActivityFeed.svelte (sport + date presets
with dynamic year pills); deploy/vps gitignored for VPS config backups.

site/src/components/ActivityFeed.svelte

@@ -39,6 +39,9 @@
 
   let all: ActivitySummary[] = [];
   let sport: Sport | 'all' = 'all';
+  let datePre = 'all';
+  let dateFrom = '';
+  let dateTo = '';
   let shown = PAGE_SIZE;
   let loading = true;
   let loadingMore = false;
@@ -53,6 +56,21 @@
   /** Logged-in handle — resolved async via bincio:me event. */
   let me: string = '';
 
+  function computeDateRange(preset: string): { dateFrom: string; dateTo: string } {
+    if (preset === 'all') return { dateFrom: '', dateTo: '' };
+    if (/^\d{4}$/.test(preset)) {
+      const y = parseInt(preset, 10);
+      return { dateFrom: `${y}-01-01T`, dateTo: `${y + 1}-01-01T` };
+    }
+    const pad = (n: number) => String(n).padStart(2, '0');
+    const now = new Date();
+    let d: Date;
+    if      (preset === '7d')  d = new Date(now.getTime() - 7  * 86_400_000);
+    else if (preset === '30d') d = new Date(now.getTime() - 30 * 86_400_000);
+    else                       { d = new Date(now); d.setMonth(d.getMonth() - 6); }
+    return { dateFrom: `${d.getFullYear()}-${pad(d.getMonth() + 1)}-${pad(d.getDate())}T`, dateTo: '' };
+  }
+
   // Show private activities only to their owner.
   // On a profile page (filterHandle set): show unlisted if me === filterHandle.
   // On the global feed: show unlisted only for the logged-in user's own activities.
@@ -63,7 +81,12 @@
     }
     return true;
   });
-  $: filtered = sport === 'all' ? withPrivacy : withPrivacy.filter(a => a.sport === sport);
+  $: allYears = [...new Set(all.map(a => a.started_at?.slice(0, 4)).filter(Boolean) as string[])].sort().reverse();
+  $: ({ dateFrom, dateTo } = computeDateRange(datePre));
+  $: withDate = !dateFrom && !dateTo ? withPrivacy : withPrivacy.filter(a =>
+    (!dateFrom || a.started_at >= dateFrom) && (!dateTo || a.started_at < dateTo)
+  );
+  $: filtered = sport === 'all' ? withDate : withDate.filter(a => a.sport === sport);
   $: visible = filtered.slice(0, shown);
   $: canShowMore = shown < filtered.length;
   $: hasMore = canShowMore || pendingShards.length > 0 || feedNextPage > 0;
@@ -99,17 +122,20 @@
     }
   }
 
-  $: if (sport) shown = PAGE_SIZE; // reset pagination on filter change
+  $: if (sport || datePre) shown = PAGE_SIZE; // reset pagination on filter change
 
   $: if (mounted) {
     const params = new URLSearchParams(window.location.search);
     if (sport === 'all') params.delete('sport'); else params.set('sport', sport);
+    if (datePre === 'all') params.delete('date'); else params.set('date', datePre);
     const qs = params.toString();
     history.replaceState(null, '', qs ? `?${qs}` : window.location.pathname);
   }
 
   onMount(async () => {
-    sport = (new URLSearchParams(window.location.search).get('sport') as Sport | 'all') ?? 'all';
+    const params = new URLSearchParams(window.location.search);
+    sport   = (params.get('sport') as Sport | 'all') ?? 'all';
+    datePre = params.get('date') ?? 'all';
     mounted = true;
 
     // Resolve the logged-in handle so we can show the owner their private activities.
@@ -161,8 +187,8 @@
   ];
 </script>
 
-<!-- Filter bar -->
-<div class="flex gap-2 mb-6 flex-wrap">
+<!-- Sport filter bar -->
+<div class="flex gap-2 mb-3 flex-wrap">
   {#each sports as s}
     <button
       class="px-3 py-1 rounded-full text-sm font-medium border transition-colors"
@@ -187,6 +213,23 @@
   {/if}
 </div>
 
+<!-- Date filter bar -->
+<div class="flex gap-2 mb-6 flex-wrap">
+  {#each [{ value: 'all', label: 'All time' }, { value: '7d', label: '7 days' }, { value: '30d', label: '30 days' }, { value: '6mo', label: '6 months' }, ...allYears.map(y => ({ value: y, label: y }))] as d}
+    <button
+      class="px-3 py-1 rounded-full text-sm font-medium border transition-colors"
+      class:border-zinc-700={datePre !== d.value}
+      class:text-zinc-400={datePre !== d.value}
+      class:border-[--accent]={datePre === d.value}
+      class:text-white={datePre === d.value}
+      style={datePre === d.value ? 'background:var(--accent-dim)' : ''}
+      on:click={() => datePre = d.value}
+    >
+      {d.label}
+    </button>
+  {/each}
+</div>
+
 {#if loading}
   <div class="grid grid-cols-1 sm:grid-cols-2 lg:grid-cols-3 gap-4">
     {#each Array(12) as _}