fix(athena): resolve 4 compatibility and correctness issues

- Use case-insensitive casing in duplicate name test to verify actual logic
- Align permission type with SDK AgentConfig pattern (as AgentConfig["permission"])
- Move duplicate-name validation from schema to runtime for graceful fallback
- Place skipped members details before 'end your turn' in council guard prompt

src/config/schema/athena.ts

@@ -20,13 +20,7 @@ export const CouncilMemberSchema = z.object({
 }).strict()
 
 export const CouncilConfigSchema = z.object({
-  members: z.array(CouncilMemberSchema).min(2).refine(
-    (members) => {
-      const names = members.map(m => m.name.toLowerCase())
-      return new Set(names).size === names.length
-    },
-    { message: "Council member names must be unique (case-insensitive)" },
-  ),
+  members: z.array(CouncilMemberSchema).min(2),
 }).strict()
 
 export type CouncilMemberConfig = z.infer<typeof CouncilMemberSchema>