Fix DM screen crash: guard hk-pane slot passthrough scope

hk-pane forwards its slots through q-scroll-area with
v-bind="scope". When a forwarded slot is invoked without props,
scope is undefined and guardReactiveProps(undefined) returns null,
so renderSlot reads null.key and the whole campaign DM screen dies
with 'Cannot read properties of null (reading key)'. Bind scope || {}
like hk-select already does.

Not caught by the route audits because hk-pane only renders on the
auth-gated Run Campaign / Run Encounter screens.

https://claude.ai/code/session_013pNZHMppjJ2iGVjxjHKkpQ

Author: claude

src/components/hk-components/hk-pane.vue

@@ -2,7 +2,9 @@
 	<Pane v-bind="$attrs">
 		<q-scroll-area :dark="$store.getters.theme === 'dark'" :thumb-style="{ width: '5px' }">
 			<template v-for="slot in Object.keys($slots)" v-slot:[slot]="scope">
-				<slot :name="slot" v-bind="scope" />
+				<!-- scope is undefined when the slot is invoked without props;
+					v-bind of a nullish value makes renderSlot throw (null.key) -->
+				<slot :name="slot" v-bind="scope || {}" />
 			</template>
 		</q-scroll-area>
 	</Pane>