fix: prepare CLAUDE.md and roomRoleContext for container reviewer

Container reviewer was running without prompts because the container
path in agent-runner.ts skipped prepareGroupEnvironment() entirely.
This meant no CLAUDE.md (platform + paired room prompts + memory
briefing) and no roomRoleContext were passed to the container.

- Add prepareContainerSessionEnvironment() to write CLAUDE.md, sync
  skills, and ensure settings.json for the reviewer session directory
- Pass roomRoleContext through ReviewerContainerInput so the runner
  can prepend the [ROOM_ROLE] header
- Add roomRoleContext field to ReviewerContainerInput interface

src/container-runner.ts

@@ -58,6 +58,7 @@ export interface ReviewerContainerInput {
   runId: string;
   isMain: boolean;
   assistantName?: string;
+  roomRoleContext?: import('./types.js').RoomRoleContext;
 }
 
 interface VolumeMount {