feat: add browser realtime talk

docs/web/control-ui.md

@@ -105,6 +105,11 @@ locale picker lives in the Gateway Access card, not under Appearance.
 ## What it can do (today)
 
 - Chat with the model via Gateway WS (`chat.history`, `chat.send`, `chat.abort`, `chat.inject`)
+- Talk to OpenAI Realtime directly from the browser via WebRTC. The Gateway
+  mints a short-lived Realtime client secret with `talk.realtime.session`; the
+  browser sends microphone audio directly to OpenAI and relays
+  `openclaw_agent_consult` tool calls back through `chat.send` for the larger
+  configured OpenClaw model.
 - Stream tool calls + live tool output cards in Chat (agent events)
 - Channels: built-in plus bundled/external plugin channels status, QR login, and per-channel config (`channels.status`, `web.login.*`, `config.patch`)
 - Instances: presence list + refresh (`system-presence`)
@@ -151,6 +156,10 @@ Cron jobs panel notes:
 - `chat.history` also strips display-only inline directive tags from visible assistant text (for example `[[reply_to_*]]` and `[[audio_as_voice]]`), plain-text tool-call XML payloads (including `<tool_call>...</tool_call>`, `<function_call>...</function_call>`, `<tool_calls>...</tool_calls>`, `<function_calls>...</function_calls>`, and truncated tool-call blocks), and leaked ASCII/full-width model control tokens, and omits assistant entries whose whole visible text is only the exact silent token `NO_REPLY` / `no_reply`.
 - `chat.inject` appends an assistant note to the session transcript and broadcasts a `chat` event for UI-only updates (no agent run, no channel delivery).
 - The chat header model and thinking pickers patch the active session immediately through `sessions.patch`; they are persistent session overrides, not one-turn-only send options.
+- Talk mode uses the registered realtime voice provider. Configure OpenAI with
+  `talk.provider: "openai"` plus `talk.providers.openai.apiKey`, or reuse the
+  Voice Call realtime provider config. The browser never receives the standard
+  OpenAI API key; it receives only the ephemeral Realtime client secret.
 - Stop:
   - Click **Stop** (calls `chat.abort`)
   - While a run is active, normal follow-ups queue. Click **Steer** on a queued message to inject that follow-up into the running turn.