fix: correct invisible text in result tiles (light mode)

Root cause: .result-tile has role="button", which triggers Pico's button
rule setting --pico-color: var(--pico-primary-inverse) = #fff in light mode.
Text inherited this white color, invisible on white card backgrounds.

Fix: override --pico-color: initial and set explicit color: var(--pico-contrast)
on .result-tile. --pico-contrast is #181c25 in light mode and #dfe3eb in dark —
both legible against their respective card backgrounds.

src/app.css

@@ -75,6 +75,11 @@
   gap: 0.2rem;
   transition: background-color 0.15s ease, border-color 0.15s ease, box-shadow 0.15s ease;
   user-select: none;
+  /* Pico's [role=button] rule sets --pico-color: var(--pico-primary-inverse)
+     which is #fff in light mode — making text invisible on white cards.
+     Override it back to the body text color on the tile itself so children inherit correctly. */
+  --pico-color: initial;
+  color: var(--pico-contrast, #181c25);
 }
 
 .result-tile:hover,
@@ -88,9 +93,7 @@
   font-weight: 600;
   font-variant-numeric: tabular-nums;
   word-break: break-all;
-  /* No explicit color — inherit from body. Pico sets this correctly for both
-     light (#373c44) and dark (#c2c7d0). Overriding with a CSS var here is
-     what caused the invisible-text regression. */
+  /* color inherits from .result-tile which has already corrected for Pico's button reset */
 }
 
 .result-label {