feat(ui): migrate entire UI to "Cozy Home" design

Warm, friendly redesign replacing the generic cold-shadcn look. Built as a
swappable token bundle so other presets can be added later; dark mode and the
user-tunable accent hue are retained.

Foundation
- app.css: warm cream (light) + "dusk" (dark) token system; terracotta accent
  (default hue 16); pastel --room-* palette; vivid --status-* (dots/bars) plus
  AA-legible --status-*-ink (text); soft warm shadows; --radius 1rem; font tokens
- Fonts: Fraunces (display) + Figtree (body), self-hosted in static/fonts
  (no Google CDN) so offline/LAN installs work; system-ui fallbacks kept
- h1/h2/h3 render in Fraunces via base layer

Chrome and surfaces
- Sidebar, Header, home, AppCard/BoardCard, BoardHeader, sections, favorites
- 29 widgets + integration renderers: cozy card shells, room-palette charts
- Default background is a static warm "cozy" glow (mesh demoted, rAF gated on
  prefers-reduced-motion)

System-wide
- Status colors tokenized (no raw bg/text-*-500 or status hex); success/warning
  to status tokens, categorical to room palette, errors to destructive
- Inputs rounded-xl; buttons rounded-xl; cards/dialogs rounded-[1.4rem];
  soft-shadow vocabulary only; focus-visible:ring-primary/30
- Forms, admin tables (now cozy cards), dialogs, popovers, auth screens

a11y: reduced-motion guards; darker status "ink" text for AA on cream.
Known tradeoff: terracotta primary + white button text ~2.96:1 (signature color,
user-tunable).

Verified: svelte-check 0/0, build ok, 274 tests pass, eslint 0 errors.
Design refs + system sheet in design-mockups/.

src/lib/components/board/BoardShareDialog.svelte

@@ -153,7 +153,7 @@
 	onclick={handleBackdropClick}
 	role="presentation"
 >
-	<div class="mx-4 w-full max-w-lg rounded-xl border border-border bg-card p-6 shadow-xl" role="dialog" aria-modal="true">
+	<div class="mx-4 w-full max-w-lg rounded-[1.4rem] border border-border bg-card p-6 shadow-[var(--shadow-lift)]" role="dialog" aria-modal="true">
 		<!-- Header -->
 		<div class="mb-4 flex items-center justify-between">
 			<h2 class="text-lg font-semibold text-card-foreground">
@@ -177,7 +177,7 @@
 			<button
 				type="button"
 				onclick={handleCopyLink}
-				class="flex items-center gap-2 rounded-lg border border-border px-3 py-2 text-sm text-foreground transition-colors hover:bg-accent"
+				class="flex items-center gap-2 rounded-xl border border-border px-3 py-2 text-sm text-foreground transition-colors hover:bg-accent"
 			>
 				<svg xmlns="http://www.w3.org/2000/svg" width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
 					<path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71" />
@@ -210,7 +210,7 @@
 				<select
 					bind:value={selectedTargetType}
 					onchange={() => { selectedTargetId = ''; searchQuery = ''; }}
-					class="rounded border border-input bg-background px-2 py-1.5 text-sm text-foreground"
+					class="rounded-xl border border-input bg-background px-2 py-1.5 text-sm text-foreground"
 				>
 					<option value={TargetType.USER}>{$t('admin.perm_user')}</option>
 					<option value={TargetType.GROUP}>{$t('admin.perm_group')}</option>
@@ -220,10 +220,10 @@
 						type="text"
 						bind:value={searchQuery}
 						placeholder={$t('board.access_search_placeholder')}
-						class="w-full rounded border border-input bg-background px-2 py-1.5 text-sm text-foreground placeholder:text-muted-foreground"
+						class="w-full rounded-xl border border-input bg-background px-2 py-1.5 text-sm text-foreground placeholder:text-muted-foreground"
 					/>
 					{#if searchQuery.length > 0 && filteredTargetOptions.length > 0 && !selectedTargetId}
-						<div class="absolute z-10 mt-1 max-h-32 w-full overflow-y-auto rounded border border-border bg-card shadow-lg">
+						<div class="absolute z-10 mt-1 max-h-32 w-full overflow-y-auto rounded-xl border border-border bg-card shadow-[var(--shadow-soft)]">
 							{#each filteredTargetOptions as option (option.id)}
 								<button
 									type="button"
@@ -238,7 +238,7 @@
 				</div>
 				<select
 					bind:value={selectedLevel}
-					class="rounded border border-input bg-background px-2 py-1.5 text-sm text-foreground"
+					class="rounded-xl border border-input bg-background px-2 py-1.5 text-sm text-foreground"
 				>
 					<option value={PermissionLevel.VIEW}>{$t('admin.perm_view')}</option>
 					<option value={PermissionLevel.EDIT}>{$t('admin.perm_edit')}</option>
@@ -248,7 +248,7 @@
 					type="button"
 					onclick={handleGrant}
 					disabled={!selectedTargetId}
-					class="shrink-0 rounded bg-primary px-3 py-1.5 text-sm font-medium text-primary-foreground hover:bg-primary/90 disabled:opacity-50"
+					class="shrink-0 rounded-xl bg-primary px-3 py-1.5 text-sm font-medium text-primary-foreground hover:bg-primary/90 disabled:opacity-50"
 				>
 					{$t('common.add')}
 				</button>