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/config/schema/athena.test.ts

@@ -41,6 +41,50 @@ describe("CouncilMemberSchema", () => {
     expect(result.success).toBe(false)
   })
 
+  test("rejects model string without provider/model separator", () => {
+    //#given
+    const config = { model: "invalid-model" }
+
+    //#when
+    const result = CouncilMemberSchema.safeParse(config)
+
+    //#then
+    expect(result.success).toBe(false)
+  })
+
+  test("rejects model string with empty provider", () => {
+    //#given
+    const config = { model: "/gpt-5.3-codex" }
+
+    //#when
+    const result = CouncilMemberSchema.safeParse(config)
+
+    //#then
+    expect(result.success).toBe(false)
+  })
+
+  test("rejects model string with empty model ID", () => {
+    //#given
+    const config = { model: "openai/" }
+
+    //#when
+    const result = CouncilMemberSchema.safeParse(config)
+
+    //#then
+    expect(result.success).toBe(false)
+  })
+
+  test("rejects empty model string", () => {
+    //#given
+    const config = { model: "" }
+
+    //#when
+    const result = CouncilMemberSchema.safeParse(config)
+
+    //#then
+    expect(result.success).toBe(false)
+  })
+
   test("rejects temperature below 0", () => {
     //#given
     const config = { model: "openai/gpt-5.3-codex", temperature: -0.1 }