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/lib/io/character.ts

@@ -0,0 +1,59 @@
+import { characterSchema, type Character } from '@/lib/schemas';
+import { newId } from '@/lib/ids';
+import { downloadJson, safeFilename } from './file';
+
+const FORMAT = 'ttrpg-manager:character';
+const VERSION = 1;
+
+interface CharacterFile {
+  format: typeof FORMAT;
+  version: number;
+  character: Character;
+}
+
+/** Download a character as a portable JSON file. */
+export function exportCharacter(c: Character): void {
+  const payload: CharacterFile = { format: FORMAT, version: VERSION, character: c };
+  downloadJson(`${safeFilename(c.name)}.character.json`, payload);
+}
+
+export class CharacterImportError extends Error {}
+
+/**
+ * Parse imported JSON into a valid Character bound to the given campaign. Accepts
+ * both our wrapped export format and a bare character object. Always assigns a
+ * fresh id + timestamps so importing never collides with or overwrites existing
+ * data.
+ */
+export function parseCharacterImport(text: string, campaignId: string): Character {
+  let raw: unknown;
+  try {
+    raw = JSON.parse(text);
+  } catch {
+    throw new CharacterImportError('That file is not valid JSON.');
+  }
+
+  const candidate =
+    raw && typeof raw === 'object' && 'character' in raw
+      ? (raw as { character: unknown }).character
+      : raw;
+
+  if (!candidate || typeof candidate !== 'object') {
+    throw new CharacterImportError('No character data found in that file.');
+  }
+
+  const now = new Date().toISOString();
+  const result = characterSchema.safeParse({
+    ...(candidate as Record<string, unknown>),
+    id: newId(),
+    campaignId,
+    createdAt: now,
+    updatedAt: now,
+  });
+  if (!result.success) {
+    throw new CharacterImportError(
+      `That file isn't a valid character: ${result.error.issues[0]?.message ?? 'unknown error'}`,
+    );
+  }
+  return result.data;
+}