fix(athena): address 6 council review findings — launcher, schema, filtering, presentation

- Forward temperature and permission through council-launcher to background manager
- Add LaunchInput.temperature and LaunchInput.permission to background-agent types
- Extract session guard with 5-minute timeout to prevent stale council locks
- Make council optional in AthenaOverrideConfigSchema for partial user overrides
- Support member lookup by both name and model ID in filterCouncilMembers
- Add provider/model-id format validation to CouncilMemberSchema
- Fix findings-presenter group header to show finding count instead of first finding's reporter count

src/features/background-agent/types.ts

@@ -87,6 +87,10 @@ export interface LaunchInput {
   skillContent?: string
   category?: string
   sessionPermission?: SessionPermissionRule[]
+  /** Per-task temperature override for council members or custom launches */
+  temperature?: number
+  /** Tool permission overrides (e.g., { write: "deny", edit: "deny" }) */
+  permission?: Record<string, "ask" | "allow" | "deny">
 }
 
 export interface ResumeInput {