feat: Archive tab — role-scoped list of archived tasks with search

New /archive page (nav link for all roles) backed by GET /api/v1/archive:
- admins see every archived task;
- consultants see archived tasks for customers they're assigned to;
- developers see archived tasks they were assigned to, claimed, or acted on.
Supports full-text ?q= search; cards link to the task detail view.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

web/static/js/archive.js

@@ -0,0 +1,44 @@
+// Archive page: archived tasks scoped by role (server-side), with search.
+import { api } from '/static/js/api.js';
+
+const host = document.getElementById('archive-list');
+const errorBox = document.getElementById('error');
+const search = document.getElementById('archive-search');
+let names = {};
+
+const esc = (s) => String(s ?? '').replace(/[&<>"']/g, (c) => ({
+  '&': '&amp;', '<': '&lt;', '>': '&gt;', '"': '&quot;', "'": '&#39;',
+}[c]));
+
+function render(tasks) {
+  host.replaceChildren(...tasks.map((t) => {
+    const card = document.createElement('div');
+    card.className = 'card';
+    const when = t.updatedAt ? new Date(t.updatedAt).toLocaleString() : '';
+    card.innerHTML = `
+      <div class="spread">
+        ${names[t.customerId] ? `<span class="card-project">${esc(names[t.customerId])}</span>` : '<span></span>'}
+        <span class="badge accent">◈ ${t.bounty}</span>
+      </div>
+      <h3 class="mt"><a href="/tasks/${t.id}">${esc(t.title)}</a></h3>
+      <p class="muted">${esc((t.description || '').slice(0, 200))}</p>
+      <p class="muted" style="font-size:0.8rem">archived${when ? ' · ' + esc(when) : ''}</p>`;
+    return card;
+  }));
+  if (!tasks.length) {
+    host.innerHTML = '<p class="muted">No archived tasks match.</p>';
+  }
+}
+
+let timer = null;
+async function load() {
+  try {
+    const q = search.value.trim();
+    const res = await api('GET', '/api/v1/archive' + (q ? '?q=' + encodeURIComponent(q) : ''));
+    names = res.customerNames || {};
+    render(res.tasks || []);
+  } catch (e) { errorBox.textContent = e.message; }
+}
+
+search.addEventListener('input', () => { clearTimeout(timer); timer = setTimeout(load, 250); });
+load();

web/templates/archive.html

@@ -0,0 +1,9 @@
+{{define "content"}}
+<h1>Archive</h1>
+<div class="error-box" id="error" role="alert"></div>
+<input type="search" id="archive-search" class="mt"
+  placeholder="Search archived tasks…" aria-label="Search archived tasks"
+  style="max-width:440px; width:100%">
+<p class="muted" style="margin-top:6px">Archived tasks you can access.</p>
+<div class="grid mt" id="archive-list"></div>
+{{end}}

web/templates/layout.html

@@ -28,6 +28,7 @@
         {{end}}
         <a href="/messages" {{if eq .Active "messages"}}aria-current="page"{{end}}>Messages</a>
         <a href="/metrics" {{if eq .Active "metrics"}}aria-current="page"{{end}}>Metrics</a>
+        <a href="/archive" {{if eq .Active "archive"}}aria-current="page"{{end}}>Archive</a>
       {{end}}
     </div>
     <div class="right">