feat(reviewer): add Tier 1 reviewer agent role with auto-channel notifications

Reviewer workflow in agent-prompts.ts (8-step process), Rust auto-post
to #review-queue on task->review transition, reviewQueueDepth in
attention scoring (10pts/task cap 50), Tasks tab for reviewer in
ProjectBox with 10s queue polling. 7 vitest + 4 cargo tests.

v2/src/lib/components/Workspace/ProjectBox.svelte

@@ -22,6 +22,8 @@
   import { ProjectId, type AgentId, type GroupId } from '../../types/ids';
   import { notify, dismissNotification } from '../../stores/notifications.svelte';
   import { registerManager, unregisterManager, updateManagerConfig } from '../../stores/wake-scheduler.svelte';
+  import { setReviewQueueDepth } from '../../stores/health.svelte';
+  import { reviewQueueCount } from '../../adapters/bttask-bridge';
 
   interface Props {
     project: ProjectConfig;
@@ -93,6 +95,23 @@
     };
   });
 
+  // Poll review queue depth for reviewer agents (feeds into attention scoring)
+  $effect(() => {
+    if (!(project.isAgent && project.agentRole === 'reviewer')) return;
+    const groupId = activeGroup?.id;
+    if (!groupId) return;
+
+    const pollReviewQueue = () => {
+      reviewQueueCount(groupId)
+        .then(count => setReviewQueueDepth(project.id, count))
+        .catch(() => {}); // best-effort
+    };
+
+    pollReviewQueue(); // immediate first poll
+    const timer = setInterval(pollReviewQueue, 10_000); // 10s poll
+    return () => clearInterval(timer);
+  });
+
   // S-1 Phase 2: start filesystem watcher for this project's CWD
   $effect(() => {
     const cwd = project.cwd;
@@ -195,6 +214,9 @@
     {#if isAgent && agentRole === 'architect'}
       <button class="ptab ptab-role" class:active={activeTab === 'architecture'} onclick={() => switchTab('architecture')}>Arch</button>
     {/if}
+    {#if isAgent && agentRole === 'reviewer'}
+      <button class="ptab ptab-role" class:active={activeTab === 'tasks'} onclick={() => switchTab('tasks')}>Tasks</button>
+    {/if}
     {#if isAgent && agentRole === 'tester'}
       <button class="ptab ptab-role" class:active={activeTab === 'selenium'} onclick={() => switchTab('selenium')}>Selenium</button>
       <button class="ptab ptab-role" class:active={activeTab === 'tests'} onclick={() => switchTab('tests')}>Tests</button>