feat(athena): council member continuation enforcer, tool allowlist, and prompt fixes

- Add council-continuation-enforcer to nudge council members until they
  output COUNCIL_MEMBER_RESPONSE, replacing the hacky post-compaction hack
- Add background_wait + background_cancel to council member tool allowlist
  so members can properly manage their explore agents before responding
- Update COUNCIL_DELEGATION_ADDENDUM prompt to instruct members to cancel
  pending tasks and wait for explore results before final response
- Fix council_finalize path resolution to use project directory
- Remove post-compaction-continuation.ts and recentlyCompactedSessions hack
- Add council-response-checker for detecting response tag in session messages

src/shared/agent-tool-restrictions.test.ts

@@ -22,12 +22,13 @@ describe("agent-tool-restrictions", () => {
     expect(restrictions.grep).toBe(true)
     expect(restrictions.call_omo_agent).toBe(true)
     expect(restrictions.background_output).toBe(true)
+    expect(restrictions.background_wait).toBe(true)
+    expect(restrictions.background_cancel).toBe(true)
     // Explicitly denied tools
     expect(restrictions.todowrite).toBe(false)
     expect(restrictions.todoread).toBe(false)
     // Unlisted tools are undefined (SDK applies wildcard at runtime)
     expect(restrictions.switch_agent).toBeUndefined()
-    expect(restrictions.background_wait).toBeUndefined()
   })
 
   test("#given dynamic council member name #when getAgentToolRestrictions #then returns council-member restrictions", () => {
@@ -43,6 +44,8 @@ describe("agent-tool-restrictions", () => {
     expect(restrictions.grep).toBe(true)
     expect(restrictions.call_omo_agent).toBe(true)
     expect(restrictions.background_output).toBe(true)
+    expect(restrictions.background_wait).toBe(true)
+    expect(restrictions.background_cancel).toBe(true)
     // Explicitly denied tools
     expect(restrictions.todowrite).toBe(false)
     expect(restrictions.todoread).toBe(false)
@@ -51,6 +54,5 @@ describe("agent-tool-restrictions", () => {
     expect(restrictions.write).toBeUndefined()
     expect(restrictions.edit).toBeUndefined()
     expect(restrictions.task).toBeUndefined()
-    expect(restrictions.background_wait).toBeUndefined()
   })
 })

src/shared/agent-tool-restrictions.ts

@@ -71,6 +71,8 @@ const AGENT_RESTRICTIONS: Record<string, Record<string, boolean>> = {
     ast_grep_search: true,
     call_omo_agent: true,
     background_output: true,
+    background_wait: true,
+    background_cancel: true,
     todowrite: false,
     todoread: false,
   },