feat(journal): add JournalContext to allow closing panel on mobile

src/components/journal/JournalContext.tsx

@@ -0,0 +1,18 @@
+/**
+ * Journal context — provides `onClose` to message renderers so that
+ * clicking a link message can close the panel on mobile.
+ */
+
+import { createContext, useContext } from "solid-js";
+
+export interface JournalContextValue {
+  onClose: () => void;
+}
+
+const JournalContext = createContext<JournalContextValue>();
+
+export function useJournalContext(): JournalContextValue | undefined {
+  return useContext(JournalContext);
+}
+
+export { JournalContext };