feat(voice): add typed AI chat beside voice

Chat sits next to the mic in the command dock. Replies are silent and never
request the microphone; the first message connects with the selected provider
and runs the same map actions as voice through each provider's text API
(OpenAI OPENAI_CHAT_MODEL, Gemini GEMINI_CHAT_MODEL via generateContent, which
never starts Live). Only one mode runs at a time.

- Chat panel rendered by the voice control presenter: conversation, recent and
  quick-command suggestions, Up/Down history, attachments (map-layer
  references or small UTF-8 text files, sent only with the message)
- Chat and voice panels sit above the dock or dock into the right rail's
  column; minimized bars sit centred above the dock, and height animates on
  swaps
- A centred panel steps down to its bar for the Location and Visual Presets
  trays without moving focus, rests above an open tray, and docks right while
  expanded over one; it returns to the centre once the trays close
- Minimized voice previews the last sentence from each side; the empty Voice
  Preview suggests things to say
- Settings opened from chat keep chat's frame and show the shared AI provider
  and quick commands; voice Settings show Back to voice
- Closing chat ends a typed session; the voice panel's close turns voice off
- The dock widens its voice control for the chat button and restyles its
  wings, which show icons only at 900px and below; assistant panels share the
  left panels' glass, and Cyber keeps its own surfaces
- Server text-chat handlers with body, time and per-IP limits
  (GEV_RATELIMIT_*_CHAT_PER_MIN), documented in SECURITY.md; tests and all
  eleven locales

Co-authored-by: Darren Dignam <[email protected]>

README.md

@@ -327,6 +327,8 @@ The standalone app offers **OpenAI** and **Gemini** in the GEV MIC provider choo
 
 Changing provider ends the current conversation. If voice is on, the new provider starts with the same open-mic or push-to-talk mode; a held Space key is not carried over. Gemini uses the same map actions and captions, but has no OpenAI cost meter or MINI tier. When Gemini reports that its session has expired, start voice again for a new conversation. The provider chooser does not change the OpenAI-backed AI HUD summary.
 
+Next to the mic, **CHAT** opens a typed chat with silent replies. It uses the selected provider and the same map actions, and never asks for the microphone. OpenAI chat needs an API key (`OPENAI_CHAT_MODEL`); Gemini chat uses a separate text model (`GEMINI_CHAT_MODEL`). Chat and voice panels sit above the dock or dock to the right.
+
 > Voice can use an **OpenAI API key** or, on the same machine, an opt-in signed-in **ChatGPT/Codex OAuth** session. The API-key path remains the default. Selecting ChatGPT OAuth in Provider Settings reuses an existing local sign-in or starts the Codex browser sign-in flow and selects OAuth when it completes. The OpenAI key still drives the **AI HUD summary**: a terse, five-word intelligence-style readout of the current view that regenerates as you move.
 
 The OAuth option is experimental. OpenAI documents ChatGPT plan usage for the [Responses API](https://developers.openai.com/siwc/token-sharing-open-source/models-and-inference); a supported third-party Realtime contract for reusing Codex tokens has not been confirmed. A successful token mint does not establish billing or support terms.