fix(background-agent): exempt council members from TTL pruning + fix promptFileMoved scope

Council members now skip TTL check in poller via isCouncilMemberAgent()
prefix match, covering both interactive (task tool) and bulk (athena_council)
launch paths. Users can cancel manually if needed.

Also fix promptFileMoved variable scoping: move declaration before try block
so finally block can access it. Dynamic timeout in error messages.

src/tools/council-archive/create-council-finalize.ts

@@ -44,6 +44,7 @@ export function createCouncilFinalize(
 
       const base = basePath ?? process.cwd()
 
+      let promptFileMoved = false
       try {
         const hexId = randomBytes(COUNCIL_DEFAULTS.ARCHIVE_ID_BYTES).toString("hex")
         const safeName = slugify(args.name) || "unnamed"
@@ -144,7 +145,7 @@ export function createCouncilFinalize(
           })
         }
 
-        let promptFileMoved = false
+
         const relPromptFile = args.prompt_file
           ? await movePromptFile(args.prompt_file, base, absArchiveDir, relArchiveDir).then((result) => {
               promptFileMoved = true