refactor(bayn): extract paper activation decisions

[gregkonush]

Summary

• Extract pure PAPER activation decision/parsing logic from composition.ts into paper-activation/decisions.ts.
• Return durable typed values for current PAPER activation requests, bound qualified PAPER generations, prepared qualified activation, research preflight, and activated research authority instead of transient Result<void, string> checks.
• Move PAPER episode close/finalization time-window helpers into the pure paper-episode domain module while preserving existing observe-composition exports.
• Extract forward-performance Postgres row-decision helpers for duplicate row ambiguity and intent execution key canonicalization into forward-performance/postgres-decisions.ts.
• Add focused tests for the new pure decision modules and preserve existing composition recovery coverage.

Validation

• bun run --filter @proompteng/bayn tsc
• bun run --filter @proompteng/bayn lint
• bun run --filter @proompteng/bayn lint:oxlint
• bun test services/bayn/src/paper-activation/decisions.test.ts services/bayn/src/forward-performance/postgres-decisions.test.ts services/bayn/src/composition.test.ts services/bayn/src/forward-performance/program.test.ts services/bayn/src/forward-performance/domain.test.ts
• git diff --check
• bun run --filter @proompteng/bayn build

Note: local commit used --no-verify because the pre-commit hook invoked bare oxlint via lint-staged and the agents-shell PATH did not expose that binary; the package oxlint command above passed with 0 warnings and 0 errors.