feat(28-02): create profile page with account management, separate from settings

Adds /profile route with four sections: profile info (reuses ProfileSection),
account info (email + member since), security (password change/set), and
danger zone (account deletion with typed confirmation). Removes ProfileSection
from settings page per D-01.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/client/hooks/useAccount.ts

@@ -0,0 +1,37 @@
+import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
+import { apiGet, apiPost } from "../lib/api";
+
+export function useHasPassword() {
+	return useQuery({
+		queryKey: ["account", "hasPassword"],
+		queryFn: () =>
+			apiGet<{ hasPassword: boolean }>("/api/account/has-password"),
+	});
+}
+
+export function useChangePassword() {
+	return useMutation({
+		mutationFn: (data: { currentPassword: string; newPassword: string }) =>
+			apiPost<{ ok: boolean }>("/api/account/password", data),
+	});
+}
+
+export function useChangeEmail() {
+	const queryClient = useQueryClient();
+	return useMutation({
+		mutationFn: (data: { newEmail: string }) =>
+			apiPost<{ ok: boolean }>("/api/account/email", data),
+		onSuccess: () => {
+			queryClient.invalidateQueries({ queryKey: ["auth"] });
+		},
+	});
+}
+
+export function useDeleteAccount() {
+	return useMutation({
+		mutationFn: () =>
+			apiPost<{ ok: boolean; redirectTo: string }>("/api/account/delete", {
+				confirmation: "DELETE",
+			}),
+	});
+}