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]>

server/providers/gemini.js

@@ -1,8 +1,13 @@
+import { createGeminiChatHandler } from './gemini/chat.js';
 import { createGeminiTokenHandler } from './gemini/realtime.js';
 
 /** Mint constrained Live API credentials; the permanent key stays on Node. */
 function geminiLiveProxy({ annotationGuidance, realtime = {} } = {}) {
   function install(middlewares) {
+    middlewares.use(
+      '/api/gemini/chat',
+      createGeminiChatHandler({ ...realtime, annotationGuidance }),
+    );
     middlewares.use(
       '/api/gemini/token',
       createGeminiTokenHandler({ ...realtime, annotationGuidance }),