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>

routes/admin_observability_routes.py

@@ -1575,6 +1575,17 @@ def budget_dashboard():
                 'cost': float(r[2] or 0),
             })
 
+        # Phase 55 S-3: 當月各 provider cost 分布（給圓餅圖用）
+        provider_cost_month = session.execute(
+            sa_text("""
+                SELECT provider, COALESCE(SUM(cost_usd), 0) AS cost
+                FROM ai_calls
+                WHERE called_at >= :ms AND cost_usd > 0
+                GROUP BY provider ORDER BY cost DESC
+            """),
+            {'ms': month_start},
+        ).fetchall()
+
         # Phase 47 K-3: top 5 cost-burning caller (當月)
         top_cost_callers = session.execute(
             sa_text("""
@@ -1643,6 +1654,10 @@ def budget_dashboard():
                 }
                 for r in top_cost_callers
             ],
+            provider_cost_month=[
+                {'provider': r[0], 'cost': float(r[1] or 0)}
+                for r in provider_cost_month
+            ],
             price_rec_7d=[
                 {
                     'strategy': r[0], 'count': int(r[1] or 0),
@@ -1656,6 +1671,7 @@ def budget_dashboard():
         return render_template('admin/budget.html', active_page='obs_budget', rows=[],
                                 budget_strategies=[], cost_trend_30d=[],
                                 top_cost_callers=[], price_rec_7d=[],
+                                provider_cost_month=[],
                                 error=f'查詢失敗: {type(e).__name__}: {str(e)[:200]}')
     finally:
         session.close()