add new GDPR page and handle account creation email

frontend/src/routes/signup/+page.svelte

@@ -189,6 +189,10 @@
 				/>
 			</label>
 			<button type="submit" disabled={submitting}>Create my family</button>
+			<p class="privacy-note">
+				By signing up you agree to our <a href="/privacy">Privacy Policy</a>. We collect your email
+				only to create and log into your account, never sell or share your data.
+			</p>
 		</form>
 		<p class="alt">Already have a family? <a href="/login">Log in</a></p>
 	{:else if step === 'child'}
@@ -381,6 +385,21 @@
 		font-size: 0.85rem;
 		color: #059669;
 	}
+	.privacy-note {
+		margin: 0.25rem 0 0;
+		font-size: 0.78rem;
+		color: #6b7280;
+		line-height: 1.5;
+		text-align: center;
+	}
+	.privacy-note a {
+		color: #4338ca;
+		text-decoration: none;
+		font-weight: 500;
+	}
+	.privacy-note a:hover {
+		text-decoration: underline;
+	}
 	.actions {
 		margin-top: 1.25rem;
 	}