fix(analytics): enforce trustworthy chart rendering

web/static/css/page-daily-sales.css

@@ -1018,6 +1018,14 @@
   letter-spacing: 0;
 }
 
+.chart-scale-note {
+  margin: 8px 0 0;
+  color: var(--momo-text-muted);
+  font-size: 11px;
+  line-height: 1.4;
+  text-align: right;
+}
+
 .chart-fallback-bars {
   position: absolute;
   inset: 0;

web/static/css/page-monthly-summary-bem.css

@@ -183,6 +183,15 @@
   font-size: var(--momo-text-body-sm, 13px);
   line-height: 1.5;
 }
+
+.ms-period-empty--error {
+  border-left-color: var(--momo-danger-text, #8f4530);
+  background: var(--momo-danger-bg, #f6e4dc);
+}
+
+.ms-period-empty--error i {
+  color: var(--momo-danger-text, #8f4530);
+}
 .ms-filter-group__label {
   display: flex; align-items: center; gap: 6px;
   font-family: var(--momo-font-display);
@@ -472,7 +481,7 @@
   }
 
   #vendorRankingChart {
-    height: 620px !important;
+    height: 460px !important;
   }
 
   #divisionDistChart,

web/static/css/page-sales-analysis-bem.css

@@ -429,6 +429,38 @@
   width: 100%;
 }
 
+.sa-chart-shell > canvas {
+  display: block;
+  width: 100% !important;
+  height: 100% !important;
+}
+
+.sa-chart-shell.chart-empty-active > canvas {
+  display: none !important;
+}
+
+.sa-chart-empty {
+  position: absolute;
+  inset: 0;
+  display: grid;
+  place-content: center;
+  gap: 6px;
+  padding: 20px;
+  color: var(--momo-text-muted);
+  text-align: center;
+}
+
+.sa-chart-empty strong {
+  color: var(--momo-text-strong);
+  font-size: 15px;
+}
+
+.sa-chart-empty span {
+  max-width: 38rem;
+  font-size: 13px;
+  line-height: 1.5;
+}
+
 /* ---------- Vendor table ---------- */
 .sa-vendor-table { max-height: 560px; overflow-y: auto; }
 .sa-vendor-table__profit {