Add collapsible left "Script State" drawer on the play screen

Exposes the scripting `state` object (every variable scripts read/write
via state.x, persisted per-adventure) in a collapsible left rail that
refreshes after each turn. New owner-scoped GET
/api/adventures/{id}/script-state endpoint; the drawer only fetches
while open and shows an empty-state hint until a script sets a variable.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TEpWMjnfPqzZ13nPMoGhs5

frontend/src/api.js

@@ -79,6 +79,7 @@ export const api = {
   // Adventures
   listAdventures: () => request('/adventures'),
   getAdventure: (id) => request(`/adventures/${id}`),
+  getScriptState: (id) => request(`/adventures/${id}/script-state`),
   createAdventure: (data) => request('/adventures', { method: 'POST', body: JSON.stringify(data) }),
   updateAdventure: (id, data) => request(`/adventures/${id}`, { method: 'PATCH', body: JSON.stringify(data) }),
   deleteAdventure: (id) => request(`/adventures/${id}`, { method: 'DELETE' }),