refactor(bayn): unify candidate lifecycle authority

[gregkonush]

Summary

• Replaces competing normalized successor kinds with one explicit candidate trial lifecycle state algebra.
• Enforces reviewed candidate -> one development attempt -> rejection or qualification eligibility -> one qualification attempt -> terminal.
• Derives qualification dormancy from canonical state; a reviewed nextCandidatePreregistration alone is never ready.
• Preserves frozen Candidate 20 PRECOMMIT_INVALID/UNATTEMPTED and next ordinal 21.

Related Issues

None

Testing

• bun test services/bayn/src/candidate-development-trials/state-machine.test.ts services/bayn/src/candidate-development-trials/qualification-dormancy.test.ts — 13 passed.
• bun run --filter @proompteng/bayn test — 1,224 passed, 153 skipped, 0 failed across 1,377 tests. PostgreSQL tests are unrelated to this pure domain-only patch and remained skipped by the suite.
• bun run --filter @proompteng/bayn tsc — passed.
• bun run --filter @proompteng/bayn lint — passed.
• bun run --filter @proompteng/bayn lint:oxlint and lint:oxlint:type — passed with one pre-existing warning outside scope in candidate-development-domain/preflight.ts.
• bunx oxfmt --check on all nine changed lifecycle files — passed.
• bun run --filter @proompteng/bayn build — passed.
• No PostgreSQL, candidate, holdout, broker, or deployment execution was performed.

Breaking Changes

None. Integration must pass the canonical CandidateDevelopmentTrialState produced/reduced by state-machine.ts to qualificationDormancyDecisionFromState; history normalization intentionally remains development-pending even when nextCandidatePreregistration is present.

Checklist

• Testing section documents the exact validation performed.
• Screenshots section is not applicable and was removed.
• Breaking Changes section is filled.
• Documentation, release notes, and follow-ups are not required for this pure internal lifecycle refactor.

[chatgpt-codex-connector]

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