fix(athena): write council prompt to .sisyphus/tmp/, switch to allow-list permissions

Council members now use an allow-list (read, grep, glob, lsp_*, ast_grep_search)
instead of a deny-list. Prompt file moved from /tmp/ to .sisyphus/tmp/ so no
external_directory permission is needed. COUNCIL_MEMBER_PROMPT is included in
the temp file for self-contained council member instructions.

src/plugin/tool-registry.ts

@@ -279,7 +279,7 @@ export function createToolRegistry(args: {
     ...(interactiveBashEnabled ? { interactive_bash: factories.interactive_bash } : {}),
     ...taskToolsRecord,
     ...hashlineToolsRecord,
-    prepare_council_prompt: createPrepareCouncilPromptTool(),
+    prepare_council_prompt: createPrepareCouncilPromptTool(ctx.directory),
   }
 
   for (const toolDefinition of Object.values(allTools)) {