Add the account area and account-synced Appearance preferences

Stage 1 PR 6 (ADR 0062). /account shows who is signed in; /account/appearance
chooses System, Light, or Dark and reduced motion (System, Reduce, Allow).

- Core: ekklesia_core_user_preference, one typed, CHECK-constrained,
  nullable column per preference (null = never chosen), migration
  0008_user_preferences (additive), @ekklesia/core/account store, and the
  authenticated-baseline permission core.account.self.manage.
- API: GET /api/v1/account (name, email, preferences) and partial
  PATCH /api/v1/account/preferences, self-only by construction: no user id
  is accepted anywhere; trusted Origin and body limit on the mutation.
- Shell: the account control shows name, email, and initials (never the
  unvetted image URL) and offers Account, Appearance, Sign out; native
  radio groups apply a choice at once through the ADR 0060 controller and
  save it; the server's answer wins and a failed save reverts.
- First paint: a classic, same-origin, render-blocking appearance.js in
  <head> applies a two-word localStorage cache before paint (no inline
  script, CSP unchanged). The account replaces the cache on every load,
  sign-out clears it, and other tabs follow via the storage event.
- Deploy smoke: real-Chromium checks for light/dark, OS emulation,
  overrides, reload persistence, pre-paint, Shadow DOM modules, reduced
  motion, the display staying light, and phone width; the browser
  container gets a 512 MiB /dev/shm so a long session no longer fails
  requests with ERR_INSUFFICIENT_RESOURCES.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

surfaces/shell/src/index.ts

@@ -19,6 +19,8 @@ export {
   type DashboardNavigationGroup,
   type DisplayHostBootstrap,
   type EkklesiaHostConfig,
+  type HostAccount,
+  type HostAccountPreferences,
   type HostBootstrap,
   type HostEventSourceFactory,
   type HostEventSourceOptions,
@@ -28,16 +30,20 @@ export {
   type HostProtocolErrorCode,
   loadDashboardNavigation,
   loadDashboardSettings,
+  loadHostAccount,
   loadHostPrincipal,
   loadModuleDisplay,
   moduleDisplayDescriptorPath,
   parseDashboardNavigation,
   parseDashboardSettings,
   parseDisplayRoute,
+  parseHostAccount,
+  parseHostAccountPreferences,
   parseHostModuleDisplay,
   parseHostPrincipal,
   resolveApiOrigin,
   resolveApiUrl,
+  saveHostAccountPreferences,
 } from "./host-protocol.js";
 export {
   type CreateModuleUiContextOptions,