v0.7.0 — retrospectives, role-based events, dispatch contracts

Highlights

• Retrospectives: the loop distills what it learned into instructions that change the next dispatch — triggered at stalls, milestones, and termination, never on a clock. Lessons are capped, cite external evidence (an oracle result, a measurement, a user correction — ungrounded self-reflection is counter-evidenced), accumulate in loop-lessons.md, and are promoted into the card's rules once confirmed twice.
• Role-based events: coordinators record dispatches, collections, and decisions in the loop log; workers record start, issue, and terminal receipts. An event a role does not write is work the record surfaces never saw.
• Dispatch and report contracts: briefs name objective, output format, tools, and boundary; worker reports pair machine answers with narrative reasons so the coordinator's decisions branch on parsable fields.

Full changelog: CHANGELOG.md