feat(10-01): wire pros/cons through client hooks, form, and card indicator

- CandidateResponse: add pros/cons string|null fields
- CandidateForm: add pros/cons to FormData, INITIAL_FORM, pre-fill, payload
- CandidateForm: add Pros/Cons textarea inputs (after Notes, before Product Link)
- CandidateCard: add pros/cons props, render purple +/- Notes badge when present
- Thread detail route: pass pros/cons props to CandidateCard

src/client/components/CandidateCard.tsx

@@ -18,6 +18,8 @@ interface CandidateCardProps {
 	isActive: boolean;
 	status: "researching" | "ordered" | "arrived";
 	onStatusChange: (status: "researching" | "ordered" | "arrived") => void;
+	pros?: string | null;
+	cons?: string | null;
 }
 
 export function CandidateCard({
@@ -33,6 +35,8 @@ export function CandidateCard({
 	isActive,
 	status,
 	onStatusChange,
+	pros,
+	cons,
 }: CandidateCardProps) {
 	const unit = useWeightUnit();
 	const currency = useCurrency();
@@ -174,6 +178,11 @@ export function CandidateCard({
 						{categoryName}
 					</span>
 					<StatusBadge status={status} onStatusChange={onStatusChange} />
+					{(pros || cons) && (
+						<span className="inline-flex items-center px-2 py-0.5 rounded-full text-xs font-medium bg-purple-50 text-purple-700">
+							+/- Notes
+						</span>
+					)}
 				</div>
 			</div>
 		</button>