feat(journal): add per-user mood journal module (task 86)

Ship journal entries with mood tracking, insights, and Recharts charts.

Adds v1 API endpoints per ADR 0005 and migration 0020_journal_entries.

src/app/journal/new/page.tsx

@@ -0,0 +1,5 @@
+import { JournalEntryEditor } from "@/modules/journal/components/entry-editor";
+
+export default function NewJournalEntryPage() {
+  return <JournalEntryEditor />;
+}