Language and theme follow the account: PATCH /me for the theme, /me's language by default

The server's /api/v2 now has PATCH /me {language, theme} and /me lists its languages and
themes. The theme is the account's and choosing one saves it there (a refusal is said);
a server whose /me lists no themes keeps the earlier choice in the app. The language is the
account's unless Settings chose this computer's or another (kept in the app, as the phone
does); a change of the account's opens the window again in it, once.

Fixtures re-pinned to the server's dev (f7f2ff2), with the new /api/v2 parity ones.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

ui/js/main.js

@@ -14,7 +14,7 @@ import { initExplorer, showLocal, showFilesTab } from "./explorer.js"
 import { initList, refreshList, markCurrent } from "./list.js"
 import { initChat, openChat, newChat, closeChat, openChatId, chatMenu, statusChanged, draftKind, onThisComputer, modelsChanged, intoComposer } from "./chat.js"
 import { initTerminal, showTerminal, terminalOpen, terminalAvailable, toggleTerminal } from "./terminal.js"
-import { applyTheme, noteAccountTheme } from "./look.js"
+import { applyTheme, noteMe } from "./look.js"
 import { initAttach, allowAttach } from "./attach.js"
 import { initPalette, openPalette } from "./palette.js"
 import { initActivity, showPanel, togglePanel, panelOpen } from "./activity.js"
@@ -92,7 +92,7 @@ async function startApp() {
   started = true
   try {
     me = await get("/me")
-    noteAccountTheme(me.theme)
+    noteMe(me)
   } catch (err) {
     $("thread-note").textContent = why(err)
     $("thread-note").hidden = false