feat(preferences): configurable photo info attributes stored in user profile

- backend: users.preferences jsonb (migration 000004), Me returns preferences, PATCH /auth/me/preferences with validation (visible list + labels)
- frontend: gear in info section opens PhotoInfoSettingsDialog; base attribute set shown by default, remaining under ellipsis; per-attribute visibility and custom labels persisted to the profile; reset clears settings from the profile
- frontend: dialog has select-all/deselect-all icon buttons (no 'show all'); EXIF constants extracted to lib/exif.ts
- fix: render modal overlays via portal to document.body so they center in the viewport despite transformed panel/rail ancestors
- openspec: sync lightroom-workspace-ui artifacts (spec/design/proposal/tasks 9.8)

frontend/src/lib/components/CreateAlbumDialog.svelte

@@ -1,5 +1,6 @@
 <script lang="ts">
 	import Icon from './Icon.svelte';
+	import { portal } from '$lib/actions/portal';
 	import { albums } from '$lib/stores/albums.svelte';
 	import type { Album } from '$lib/types';
 
@@ -42,6 +43,7 @@
 <svelte:window onkeydown={onKey} />
 
 <div
+	use:portal
 	class="fixed inset-0 z-50 flex items-center justify-center bg-black/50 p-4"
 	role="dialog"
 	aria-modal="true"