bregctl dev: live lifecycle test ports, undocumented deadlines, verify_outputs coverage, Postgres digest in DEV.md

[jeremi]

1. crates/registry-bregctl/tests/dev_lifecycle.rs uses three fixed ports (BReg on 8094 among them), so two concurrent runs collide. Pick free ports the way the supervisor does.
2. The 120 s child deadline and the 45 s readiness deadlines in crates/registry-bregctl/src/dev/mod.rs are stated neither in products/breg/DEV.md nor in the CLI reference.
3. The supervisor's failure and recovery arms gained unit coverage in feat(evidence): compose BReg lookups as native Evidence sources #865; verify_outputs after a partial start did not.
4. The pinned postgres:17.11 digest lives only in dev/mod.rs. State it in products/breg/DEV.md and the reference page so an operator can check what the supervisor pulls.

Origin: review of PR #865.