feat(narrative): session store single source of truth and bidirectional route sync

[lark-x]

Summary

• Consolidated all Narrative Workbench UI state (\mode, \�ctiveSceneId, \�ctiveQuestId, \�ctiveBlockId, panel visibility) into \useNarrativeSessionStore.
• Created \useNarrativeRouteSync\ for bidirectional, non-cyclic synchronization between URL Query params (?mode=..., ?scene=..., ?quest=..., ?panel=...) and Session Store.
• Supports browser Back/Forward navigation, page refresh preservation, and deep linking directly into specific scenes/modes.
• Added comprehensive unit tests in \useNarrativeSessionStore.test.ts.