feat: lightroom-style workspace UI with album covers

Backend:
- expose cover thumbnail URL on album responses (LEFT JOIN + presign)
- auto-assign cover only when empty; FK cover_photo_id -> photos ON DELETE SET NULL
- add photos_count / members_count to album responses; cover repo test

Frontend:
- split layouts into (app) shell (resizable rail + contextual panel) and (public)
- album rail + create-album dialog; album panel with cover picker / make-cover
- photo viewer route with filmstrip, replacing lightbox; share reuses it
- grid density slider, toolbar + drag-and-drop upload, dark graphite default

OpenSpec: add lightroom-workspace-ui change (proposal, design, specs, tasks)

frontend/src/routes/(public)/login/+page.svelte

@@ -0,0 +1,85 @@
+<script lang="ts">
+	import { goto } from '$app/navigation';
+	import { authApi } from '$lib/api';
+	import { auth } from '$lib/stores/auth.svelte';
+
+	let mode = $state<'login' | 'register'>('login');
+	let email = $state('');
+	let password = $state('');
+	let name = $state('');
+	let error = $state('');
+	let busy = $state(false);
+
+	async function submit(ev: Event) {
+		ev.preventDefault();
+		error = '';
+		busy = true;
+		try {
+			const data =
+				mode === 'login'
+					? await authApi.login(email, password)
+					: await authApi.register(email, password, name);
+			auth.setTokens(data.tokens);
+			auth.setUser(data.user);
+			goto('/');
+		} catch (e) {
+			error = (e as Error).message;
+		} finally {
+			busy = false;
+		}
+	}
+</script>
+
+<div class="mx-auto max-w-sm py-10">
+	<h1 class="mb-6 text-2xl font-bold">{mode === 'login' ? 'Вход' : 'Регистрация'}</h1>
+
+	<form class="space-y-4" onsubmit={submit}>
+		{#if mode === 'register'}
+			<label class="block">
+				<span class="text-text-muted mb-1 block text-sm">Имя</span>
+				<input
+					bind:value={name}
+					required
+					class="border-border bg-bg-elevated text-text w-full rounded-lg border px-3 py-2"
+				/>
+			</label>
+		{/if}
+		<label class="block">
+			<span class="text-text-muted mb-1 block text-sm">Email</span>
+			<input
+				bind:value={email}
+				type="email"
+				required
+				class="border-border bg-bg-elevated text-text w-full rounded-lg border px-3 py-2"
+			/>
+		</label>
+		<label class="block">
+			<span class="text-text-muted mb-1 block text-sm">Пароль</span>
+			<input
+				bind:value={password}
+				type="password"
+				required
+				minlength="8"
+				class="border-border bg-bg-elevated text-text w-full rounded-lg border px-3 py-2"
+			/>
+		</label>
+
+		{#if error}<p class="text-danger text-sm">{error}</p>{/if}
+
+		<button
+			type="submit"
+			disabled={busy}
+			class="bg-primary text-primary-fg w-full rounded-lg px-4 py-2.5 font-medium disabled:opacity-50"
+		>
+			{busy ? 'Подождите…' : mode === 'login' ? 'Войти' : 'Зарегистрироваться'}
+		</button>
+	</form>
+
+	<button
+		type="button"
+		class="text-primary mt-4 text-sm"
+		onclick={() => (mode = mode === 'login' ? 'register' : 'login')}
+	>
+		{mode === 'login' ? 'Нет аккаунта? Зарегистрироваться' : 'Уже есть аккаунт? Войти'}
+	</button>
+</div>