Hide unconfigured realtime voice providers

[rogerchappel]

Summary

• add a typed OpenClaw gateway client wrapper for talk.catalog
• filter OpenAI/Google realtime voice options from the primary readable runtime's configured realtime providers
• hide voice provider filter chips when no voices are available for that provider

Verification

• pnpm typecheck
• git diff --check
• pnpm test -- src/lib/realtime-voice-client.test.ts src/lib/runtime-capabilities.test.ts
• push hook: pnpm typecheck && pnpm build

Notes

• If talk.catalog is unavailable or the runtime cannot be read, the voice list falls back to the existing static behavior.
• Build completed with the existing Turbopack NFT tracing warning for next.config.ts -> openclaw-config-parser -> runtimes/probe.