Show toast and open source panel when rolling initiative without loaded source

When a user clicks the d20 to roll initiative for a single combatant whose
bestiary source isn't cached, show an informative toast and open the stat
block panel so they can load the source directly.

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

apps/web/src/App.tsx

@@ -117,6 +117,7 @@ export function App() {
 	const sidePanel = useSidePanelState();
 
 	const [rollSkippedCount, setRollSkippedCount] = useState(0);
+	const [rollSingleSkipped, setRollSingleSkipped] = useState(false);
 
 	const selectedCreature: Creature | null = sidePanel.selectedCreatureId
 		? (getCreature(sidePanel.selectedCreatureId) ?? null)
@@ -145,9 +146,21 @@ export function App() {
 
 	const handleRollInitiative = useCallback(
 		(id: CombatantId) => {
-			rollInitiativeUseCase(makeStore(), id, rollDice(), getCreature);
+			const result = rollInitiativeUseCase(
+				makeStore(),
+				id,
+				rollDice(),
+				getCreature,
+			);
+			if (isDomainError(result)) {
+				setRollSingleSkipped(true);
+				const combatant = encounter.combatants.find((c) => c.id === id);
+				if (combatant?.creatureId) {
+					sidePanel.showCreature(combatant.creatureId);
+				}
+			}
 		},
-		[makeStore, getCreature],
+		[makeStore, getCreature, encounter.combatants, sidePanel.showCreature],
 	);
 
 	const handleRollAllInitiative = useCallback(() => {
@@ -363,6 +376,14 @@ export function App() {
 				/>
 			)}
 
+			{!!rollSingleSkipped && (
+				<Toast
+					message="Can't roll — bestiary source not loaded"
+					onDismiss={() => setRollSingleSkipped(false)}
+					autoDismissMs={4000}
+				/>
+			)}
+
 			<PlayerCharacterSection
 				ref={playerCharacterRef}
 				characters={playerCharacters}