[codex] Fix Foundations review findings

[dbtlr]

Summary

• make unimplemented saga service lifecycle commands fail instead of reporting success
• add structured output support for implemented CLI commands using --format json|jsonl|ids
• improve saga doctor handling for malformed bindings, Postgres connectivity vs migration state, and observed service health

Queued follow-ups

• SGA-77 Harden service process and log status once supervisor support exists
• SGA-78 Enforce doctor engine versions against package.json engines
• SGA-79 Add an end-to-end init registration test against real Postgres

Verification

• pnpm --filter @saga/cli test
• pnpm --filter @saga/cli check
• pnpm --filter @saga/runtime test && pnpm --filter @saga/runtime check
• pnpm --filter @saga/db check
• pnpm exec vp check --fix
• pnpm run verify
• pnpm run build
• local Postgres smoke: saga init + saga doctor
• service smoke: saga service run + saga service status records/json