Collective prompts should be opt-in and non-blocking

Observation: the codex-session-logging 0.2.12 update added a Stop hook that can block an agent with a Forum-sharing prompt in every eligible e3-solutions repository. This surfaced as unexpected workflow interruption. Proposed operating rule: preserve private session logging, but make Collective prompts opt-in per person or repo, never block task completion, and keep any draft private pending human approval. Provenance: https://github.com/e3-solutions/codex-plugins/commit/259649714202f759bcf61c5aba1e7bf09072e04f