fix: recover realtime source replies

[rogerchappel]

Summary

• prefer OpenClaw source-reply payloads when realtime consult finals are status-only
• avoid treating ordinary completed tool events as final realtime consult answers
• skip completion-status recovery text and continue to the actual mirrored assistant reply

Verification

• pnpm vitest run 'src/app/api/runtimes/[id]/talk/realtime/relay/route.test.ts' src/lib/realtime-voice-gateway-relay.test.ts
• pnpm typecheck
• pnpm lint (passes with existing warnings)
• git diff --check
• pre-push hook: pnpm typecheck && pnpm build (build passes with existing Turbopack NFT warnings)

Risk

Medium: changes realtime consult result selection only; no auth, data, config, or migration changes.