Fix: card text contrast, stable grid order, independent highlight/input states, highlight dismiss

- Explicit dark colors on .result-value, .result-label, .result-symbol, .highlighted-value, .highlighted-label
- Include from-unit in results grid (stable definition-order); from-unit tile shows Big(inputValue) and gets is-input-unit dashed-border class
- Shift+click no longer clears highlightedUnitId — fromUnitId and highlightedUnitId are now fully independent states
- Add × dismiss button (aria-label="Remove highlight") to .highlighted-result banner; .highlighted-result gains position:relative

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/app.css

@@ -68,16 +68,17 @@
   font-weight: 600;
   font-variant-numeric: tabular-nums;
   word-break: break-all;
+  color: #2C2C2C; /* explicit dark charcoal, do not rely on inheritance */
 }
 
 .result-label {
   font-size: 0.85rem;
-  color: var(--pico-muted-color, #666);
+  color: #555550;
 }
 
 .result-symbol {
   font-size: 0.75rem;
-  color: var(--pico-muted-color, #666);
+  color: #888880;
   font-style: italic;
 }
 
@@ -94,6 +95,7 @@
   flex-direction: column;
   align-items: center;
   gap: 0.4rem;
+  position: relative;
 }
 
 .highlighted-value {
@@ -102,11 +104,12 @@
   font-variant-numeric: tabular-nums;
   line-height: 1.1;
   word-break: break-all;
+  color: #2C2C2C;
 }
 
 .highlighted-label {
   font-size: 1.25rem;
-  color: var(--pico-color, inherit);
+  color: #2C2C2C;
 }
 
 .highlighted-symbol {
@@ -133,6 +136,34 @@
   min-width: 160px;
 }
 
+/* ── Input unit tile indicator ─────────────────────────────────────────────── */
+.result-tile.is-input-unit {
+  border-style: dashed;
+  border-color: var(--pico-primary);
+  opacity: 0.85;
+}
+
+/* ── Highlight dismiss button ──────────────────────────────────────────────── */
+.highlight-dismiss {
+  position: absolute;
+  top: 0.5rem;
+  right: 0.75rem;
+  background: none;
+  border: none;
+  cursor: pointer;
+  font-size: 1rem;
+  line-height: 1;
+  color: var(--pico-muted-color, #888);
+  padding: 0.15rem 0.3rem;
+  border-radius: 0.2rem;
+  transition: color 0.15s ease, background-color 0.15s ease;
+}
+
+.highlight-dismiss:hover {
+  color: #2C2C2C;
+  background-color: rgba(0, 0, 0, 0.06);
+}
+
 /* ── Hotkey hint ───────────────────────────────────────────────────────────── */
 .hotkey-hint {
   margin-top: 1rem;