Cline v4.1.20 runs same-step sub-agent tool calls in parallel

Cline released v4.1.20 on Sep 22: sub-agents spawned in the same step now execute their tool calls concurrently instead of sequentially, reducing wall-clock time for fan-out tasks. Two SDK releases the same day — sdk/v0.0.84 and sdk/v0.0.85 — add retry on runs that hit output-token limits without a usable tool call, and dedupe concurrent feature-flag polls.