v2.93.3

fix: subagent generation silently fails due to bash arithmetic exit code

• Fixed ((subagent_count++)) with set -euo pipefail silently killing the script when counter is 0
• Post-increment evaluates current value (0) first, which is falsy (exit code 1)
• Replaced with subagent_count=$((subagent_count + 1)) which always returns exit code 0
• All 596 subagent files now correctly generated in ~/.config/opencode/agent/