feat(athena): add dedicated council-member agent for multi-model council

Replace oracle as the agent for council background tasks with a purpose-built

council-member agent. This avoids coupling to oracle's config/prompt and provides

proper read-only tool restrictions (deny write, edit, task, athena_council).

- New council-member-agent.ts with analysis-oriented system prompt

- Registered in agentSources (hidden from Sisyphus delegation table)

- Added to type system, Zod schemas, display names, tool restrictions

- Minimal model fallback (always overridden per council member at launch)

- Council orchestrator now launches members as council-member agent

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-opencode)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/shared/agent-tool-restrictions.ts

@@ -52,6 +52,14 @@ const AGENT_RESTRICTIONS: Record<string, Record<string, boolean>> = {
   },
 
   athena: ATHENA_RESTRICTIONS,
+
+  "council-member": {
+    write: false,
+    edit: false,
+    task: false,
+    call_omo_agent: false,
+    athena_council: false,
+  },
 }
 
 function permissionToToolBooleans(

src/shared/model-requirements.ts

@@ -191,6 +191,11 @@ export const AGENT_MODEL_REQUIREMENTS: Record<string, ModelRequirement> = {
       { providers: ["google", "github-copilot", "opencode"], model: "gemini-3-pro", variant: "high" },
     ],
   },
+  "council-member": {
+    fallbackChain: [
+      { providers: ["opencode"], model: "gpt-5-nano" },
+    ],
+  },
 };
 
 export const CATEGORY_MODEL_REQUIREMENTS: Record<string, ModelRequirement> = {