feat(p55): 3 個圓餅圖補齊 — promotion_review/ppt_audit/budget

S-1: promotion_review 蒸餾池 30d doughnut
- 取代原 col-md-2 卡片網格
- 8 種狀態各自分色：
  pending(灰) / awaiting_review(黃) / approved(綠) /
  rejected_quality(紅) / rejected_hallucination(深紅) /
  rejected_duplicate(橘) / rejected_human(暗紅) / expired(灰)
- 左圓餅 + 右表格雙視角

S-2: ppt_audit 30d 結果 doughnut
- 取代部分 col-md-2 卡片佈局
- 通過(綠)/失敗(黃)/錯誤(紅)/跳過(灰) 圓餅
- 6 個 KPI 卡併入右側 col-6 grid（總筆數/通過率/通過/issue/失敗/錯誤）
- 統一視覺語言：「圖+表」雙視角

S-3: budget 當月各 provider 成本 doughnut
- 新加 query：ai_calls.cost_usd GROUP BY provider 月初至今
- 8 個 provider 分色（本地 Ollama 綠系 vs 付費 LLM 橘紫系）
- 左圓餅 + 右表格（供應商/成本/佔比）+ 總計列

chart.js 視覺化從 7 個 → 10 個：
- hourly trend line
- 30d cost stacked bar
- 三主機 sparkline × 3
- RAG feedback doughnut
- KPI sparkline × 3 (calls/cost/errors)
- verdict doughnut
- heal 7d trend
- **promotion_review status doughnut（新）**
- **ppt_audit pass/fail doughnut（新）**
- **provider cost doughnut（新）**

Phase 38→55 累計 20 commits / 10 觀測頁 / 10 chart.js / DB 100%。

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

templates/admin/budget.html

@@ -99,6 +99,44 @@
     </tbody>
   </table>
 
+  <!-- Phase 55 S-3: 當月各 provider 成本分布圓餅 -->
+  {% if provider_cost_month %}
+  <div class="card mb-3">
+    <div class="card-header"><strong><i class="fas fa-chart-pie me-2"></i>當月各供應商成本分布</strong>
+      <small class="text-muted">資料來源：ai_calls.cost_usd GROUP BY provider · 月初至今</small>
+    </div>
+    <div class="card-body">
+      <div class="row g-2 align-items-center">
+        <div class="col-md-5">
+          <canvas id="providerCostPieChart" height="180"></canvas>
+        </div>
+        <div class="col-md-7">
+          <table class="table table-sm mb-0" style="font-size: 0.9em;">
+            <thead class="table-light">
+              <tr><th>供應商</th><th class="text-end">成本</th><th class="text-end">佔比</th></tr>
+            </thead>
+            <tbody>
+              {% set total_pc = (provider_cost_month | sum(attribute='cost')) or 0.0001 %}
+              {% for p in provider_cost_month %}
+              <tr>
+                <td><code>{{ p.provider }}</code></td>
+                <td class="text-end">${{ "%.4f"|format(p.cost) }}</td>
+                <td class="text-end">{{ "%.1f"|format(p.cost / total_pc * 100) }}%</td>
+              </tr>
+              {% endfor %}
+              <tr style="border-top: 2px solid #dee2e6;">
+                <td><strong>總計</strong></td>
+                <td class="text-end"><strong>${{ "%.2f"|format(total_pc) }}</strong></td>
+                <td class="text-end"><strong>100%</strong></td>
+              </tr>
+            </tbody>
+          </table>
+        </div>
+      </div>
+    </div>
+  </div>
+  {% endif %}
+
   <!-- Phase 47 K-3: Top 5 cost-burning caller -->
   {% if top_cost_callers %}
   <div class="card mb-3">
@@ -173,6 +211,39 @@
 
 <script src="https://cdn.jsdelivr.net/npm/chart.js@4.4.1/dist/chart.umd.min.js"></script>
 <script>
+// Phase 55 S-3: provider 月度成本圓餅
+(function() {
+  const data = {{ provider_cost_month | default([]) | tojson }};
+  const el = document.getElementById('providerCostPieChart');
+  if (!el || !data.length) return;
+  const colors = {
+    'gcp_ollama': '#28a745', 'ollama_secondary': '#5cb85c', 'ollama_111': '#a3d9a4',
+    'gemini': '#fd7e14', 'claude': '#6610f2', 'nim': '#0dcaf0',
+    'openrouter': '#6c757d', 'nim_via_elephant': '#20c997',
+  };
+  new Chart(el, {
+    type: 'doughnut',
+    data: {
+      labels: data.map(d => d.provider),
+      datasets: [{
+        data: data.map(d => d.cost),
+        backgroundColor: data.map((d, i) => colors[d.provider] || `hsl(${(i*47)%360}, 65%, 55%)`),
+        borderWidth: 1, borderColor: '#fff',
+      }]
+    },
+    options: {
+      responsive: true, maintainAspectRatio: false,
+      plugins: {
+        legend: { position: 'right', labels: { font: { size: 11 } } },
+        tooltip: { callbacks: { label: c => {
+          const total = data.reduce((a,b)=>a+b.cost, 0);
+          return `${c.label}: $${c.parsed.toFixed(4)} (${(c.parsed/total*100).toFixed(1)}%)`;
+        }}}
+      }
+    }
+  });
+})();
+
 // Phase 50 N-2: 30d cost trend stacked bar chart
 (function() {
   const raw = {{ cost_trend_30d | tojson }};