Fixes + UX: combat HP, char delete, dice animation, compendium filters, import/export

- Combat: relabel HP controls Dmg/Heal, disabled at 0 (were silent no-ops)
- Characters: per-card Delete (confirm) + Export; header Import from JSON
- Dice: tumbling roll animation that settles on the result (a11y-safe)
- Compendium: per-category filters (monster type/CR, spell level/school, item rarity/type) + Clear
- Character import/export to portable JSON (reassigns id, validates on import)
- New: 4 io unit tests, e2e fixes spec (HP damage, delete, CR filter)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/styles/globals.css

@@ -84,3 +84,43 @@ body {
   scrollbar-width: thin;
   scrollbar-color: var(--app-line) transparent;
 }
+
+/* Dice roll animations */
+@keyframes dice-tumble {
+  0% {
+    transform: scale(0.7) rotate(-12deg);
+    opacity: 0.5;
+  }
+  50% {
+    transform: scale(1.12) rotate(8deg);
+  }
+  75% {
+    transform: scale(0.96) rotate(-3deg);
+  }
+  100% {
+    transform: scale(1) rotate(0deg);
+    opacity: 1;
+  }
+}
+.animate-dice-settle {
+  animation: dice-tumble 0.45s cubic-bezier(0.22, 1, 0.36, 1);
+}
+
+@keyframes dice-shake {
+  0%,
+  100% {
+    transform: translate(0, 0) rotate(0deg);
+  }
+  25% {
+    transform: translate(-2px, 1px) rotate(-3deg);
+  }
+  50% {
+    transform: translate(2px, -1px) rotate(3deg);
+  }
+  75% {
+    transform: translate(-1px, 2px) rotate(-2deg);
+  }
+}
+.animate-dice-rolling {
+  animation: dice-shake 0.12s linear infinite;
+}