feat(agents): enable call_omo_agent for Sisyphus-Junior subagents

Allow Sisyphus-Junior (category-based tasks) to spawn explore/librarian
agents via call_omo_agent for research capabilities.

Changes:
- Remove call_omo_agent from BLOCKED_TOOLS in sisyphus-junior.ts
- Update prompt to show ALLOWED status for call_omo_agent
- Remove global call_omo_agent blocking in config-handler.ts
- Keep blocking for orchestrator-sisyphus (use sisyphus_task instead)
- Keep runtime recursion prevention in index.ts for explore/librarian

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

src/tools/call-omo-agent/tools.ts

@@ -176,7 +176,6 @@ async function executeSync(
         agent: args.subagent_type,
         tools: {
           task: false,
-          call_omo_agent: false,
           sisyphus_task: false,
         },
         parts: [{ type: "text", text: args.prompt }],