fix: sync council-member tool restrictions across all layers, optimize athena guards

- Add switch_agent/background_wait to agent-tool-restrictions.ts (boolean format)
- Add dynamic council member name matching via COUNCIL_MEMBER_KEY_PREFIX
- Move athena question permission from hardcoded to tool-config-handler (CLI-mode aware)
- Rename appendMissingCouncilPrompt -> applyMissingCouncilGuard
- Optimize tool-execute-before: check hasPendingCouncilMembers before resolving session agent
- Add fallback_models to council-member/athena in schema.json
- Remove unused createAthenaAgent export from agents/index.ts
- Add cross-reference comments for restriction sync points

src/agents/builtin-agents/athena-council-guard.ts

@@ -45,7 +45,7 @@ After informing the user, **end your turn**. Do NOT try to work around this by u
  * The original prompt is discarded to avoid contradictory instructions.
  * Used when Athena is registered but no valid council config exists.
  */
-export function appendMissingCouncilPrompt(
+export function applyMissingCouncilGuard(
   athenaConfig: AgentConfig,
   skippedMembers?: Array<{ name: string; reason: string }>,
 ): AgentConfig {