feat: add api_input LED interpolation; fix LED preview, FPS charts, dashboard layout

API Input:
- Add interpolation mode (linear/nearest/none) for LED count mismatch
  between incoming data and device LED count
- New IconSelect in editor, i18n for en/ru/zh
- Mark crossfade as won't-do (client owns temporal transitions)
- Mark last-write-wins as already implemented

LED Preview:
- Fix zone-mode preview parsing composite wire format (0xFE header
  bytes were rendered as color data, garbling multi-zone previews)
- Fix _restoreLedPreviewState to handle zone-mode panels

FPS Charts:
- Seed target card charts from server metrics-history on first load
- Add fetchMetricsHistory() with 5s TTL cache shared across
  dashboard, targets, perf-charts, and graph-editor
- Fix chart padding: pass maxSamples per caller (120 for dashboard,
  30 for target cards) instead of hardcoded 120
- Fix dashboard chart empty on tab switch (always fetch server history)
- Left-pad with nulls for consistent chart width across targets

Dashboard:
- Fix metrics row alignment (grid layout with fixed column widths)
- Fix FPS label overflow into uptime column

server/src/wled_controller/static/css/dashboard.css

@@ -158,14 +158,15 @@
 }
 
 .dashboard-target-metrics {
-    display: flex;
-    gap: 12px;
+    display: grid;
+    grid-template-columns: auto 72px 36px;
+    gap: 8px;
     align-items: center;
 }
 
 .dashboard-metric {
     text-align: center;
-    min-width: 48px;
+    overflow: hidden;
 }
 
 .dashboard-metric-value {
@@ -174,6 +175,7 @@
     color: var(--primary-text-color);
     line-height: 1.2;
     font-family: var(--font-mono, monospace);
+    white-space: nowrap;
 }
 
 .dashboard-metric-label {
@@ -187,7 +189,7 @@
     display: flex;
     align-items: center;
     gap: 6px;
-    min-width: auto;
+    overflow: hidden;
 }
 
 .dashboard-fps-sparkline {
@@ -200,7 +202,8 @@
     display: flex;
     flex-direction: column;
     align-items: center;
-    min-width: 36px;
+    width: 44px;
+    flex-shrink: 0;
     line-height: 1.1;
 }