- [x] Add journal section/tab to the run detail page
- [x] Add route for journal entry detail/edit view
## Summary of Changes
Implemented the frontend journal entry editor and list view with the following components:
**Types created:**
-`frontend/src/types/journal.ts` - TypeScript types for JournalEntry, CreateJournalEntryInput, UpdateJournalEntryInput
**API client created:**
-`frontend/src/api/journal.ts` - CRUD functions for journal entries
-`frontend/src/hooks/useJournal.ts` - React Query hooks for journal data fetching and mutations
**Components created:**
-`frontend/src/components/journal/JournalList.tsx` - Chronological list of entries with title, date, preview snippet, and linked boss display
-`frontend/src/components/journal/JournalEditor.tsx` - Markdown textarea with title input, boss result selector, write/preview tabs, save/delete actions
-`frontend/src/components/journal/JournalEntryView.tsx` - Rendered markdown display with entry metadata
-`frontend/src/components/journal/JournalSection.tsx` - Wrapper component for embedding in RunEncounters page
**Pages created:**
-`frontend/src/pages/JournalEntryPage.tsx` - Standalone page for viewing/editing a single journal entry
**Modified files:**
-`frontend/src/types/index.ts` - Added journal type exports