v1.1.2: action button, responsive faders, label scaling

Third integration-feedback release from building the streaming studio.

- New `Button` — a click-to-fire command button in the panel style, the
  non-latching sibling of PushButton. Implemented as PushButton's new
  `mode="action"` (never latches, press-down + brief LED flash, `onClick`);
  led="dot" (default) matches the corner-dot look, led={false} is plain.
- `fill` on LEDFader (parity with Fader) — faders stretch to fill their
  container in resizable panels instead of a fixed pixel length.
- `labelSize` on IndicatorLamp (and LampRow) — shrink the caption below its
  10px floor to match dense header rows.
- Docs: a dedicated "Buttons & switches" section with a decision guide
  (Button/PushButton/TransportButton/ToggleSwitch/SegmentSwitch) + live demos.

Library + docs typecheck and build; 38 tests pass.

apps/docs/src/styles.css

@@ -353,6 +353,76 @@ h2.section-title {
   text-transform: uppercase;
 }
 
+/* Buttons section: decision guide + live demo grid */
+.guide-grid {
+  display: flex;
+  flex-direction: column;
+  gap: 1px;
+  margin: 8px 0 28px;
+  border-radius: 12px;
+  overflow: hidden;
+  border: 1px solid var(--line);
+  background: var(--line);
+}
+.guide-row {
+  display: grid;
+  grid-template-columns: 190px 1fr;
+  gap: 4px 18px;
+  align-items: baseline;
+  padding: 12px 16px;
+  background: #101219;
+}
+.guide-code {
+  font-family: var(--font-mono);
+  font-size: 13px;
+  color: #4cc2ff;
+}
+.guide-when {
+  font-size: 14px;
+  color: var(--text);
+}
+.guide-eg {
+  grid-column: 2;
+  font-size: 12.5px;
+  color: var(--text-dim);
+}
+.btn-demo {
+  display: grid;
+  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
+  gap: 12px;
+}
+.btn-demo-cell {
+  display: flex;
+  flex-direction: column;
+  gap: 14px;
+  padding: 18px;
+  border-radius: 12px;
+  background: linear-gradient(180deg, #16181f, #0e0f14);
+  border: 1px solid var(--line-strong);
+}
+.btn-demo-label {
+  font-family: var(--font-mono);
+  font-size: 11px;
+  letter-spacing: 0.08em;
+  color: var(--text-dim);
+  text-transform: uppercase;
+}
+.btn-demo-row {
+  display: flex;
+  align-items: center;
+  gap: 12px;
+  flex-wrap: wrap;
+  min-height: 40px;
+}
+@media (max-width: 560px) {
+  .guide-row {
+    grid-template-columns: 1fr;
+  }
+  .guide-eg {
+    grid-column: 1;
+  }
+}
+
 /* ---- synth panel ---- */
 .synth-rows {
   display: flex;