feat: BindableFloat — universal value source binding for all scalar properties

Introduce BindableFloat abstraction that allows any numeric property to be
either a static value or dynamically driven by a ValueSource. Backward-compatible
serialization: plain float when unbound, {value, source_id} dict when bound.

Backend:
- storage/bindable.py — BindableFloat dataclass + bfloat() helper
- 25+ scalar properties converted across all entity types
- Runtime VS acquisition in ColorStripStreamManager for CSS bindings
- All stream hot loops use self.resolve() for live values
- KeyColorsColorStripStream now inherits ColorStripStream

Frontend:
- BindableScalarWidget (slider + VS picker toggle) for all editors
- TypeScript BindableFloat type + helpers
- Graph editor edges for all bindable properties
- Audio source channel IconSelect grid

Fixes: daylight longitude, candlelight wind_strength/candle_type from_dict

server/src/wled_controller/static/css/components.css

@@ -1109,3 +1109,69 @@ textarea:focus-visible {
     text-align: right;
     font-variant-numeric: tabular-nums;
 }
+
+/* ── BindableScalarWidget ── */
+
+.bindable-slider-row,
+.bindable-vs-row {
+    display: flex;
+    align-items: center;
+    gap: 8px;
+}
+
+.bindable-slider-row input[type="range"] {
+    flex: 1;
+    min-width: 0;
+}
+
+.bindable-vs-row select,
+.bindable-vs-row .entity-select-btn {
+    flex: 1;
+    min-width: 0;
+}
+
+.bindable-value {
+    min-width: 3.5ch;
+    text-align: right;
+    font-variant-numeric: tabular-nums;
+    color: var(--text-secondary);
+    font-size: 0.85rem;
+}
+
+.bindable-toggle {
+    flex-shrink: 0;
+    width: 26px;
+    height: 26px;
+    padding: 3px;
+    border: 1px solid var(--border-color);
+    border-radius: var(--radius);
+    background: var(--bg-secondary);
+    cursor: pointer;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    color: var(--text-secondary);
+    transition: color 0.15s, border-color 0.15s, background 0.15s;
+}
+
+.bindable-toggle:hover {
+    border-color: var(--primary-color);
+    color: var(--primary-color);
+}
+
+.bindable-toggle--active {
+    background: var(--primary-color);
+    border-color: var(--primary-color);
+    color: var(--bg-color);
+}
+
+.bindable-toggle--active:hover {
+    opacity: 0.85;
+    color: var(--bg-color);
+}
+
+.bindable-toggle .icon-xs {
+    width: 16px;
+    height: 16px;
+    fill: currentColor;
+}