feat: add setup impact preview UI with delta badges across all views

Adds SetupImpactSelector dropdown and ImpactDeltaBadge inline badge, wired into the thread detail page. Delta badges appear on CandidateListItem, CandidateCard, and ComparisonTable (Weight Impact / Price Impact rows) whenever a setup is selected for comparison.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/client/components/CandidateCard.tsx

@@ -1,7 +1,9 @@
 import { useFormatters } from "../hooks/useFormatters";
+import type { CandidateDelta } from "../hooks/useImpactDeltas";
 import { LucideIcon } from "../lib/iconData";
 import { useUIStore } from "../stores/uiStore";
 import { RankBadge } from "./CandidateListItem";
+import { ImpactDeltaBadge } from "./ImpactDeltaBadge";
 import { StatusBadge } from "./StatusBadge";
 
 interface CandidateCardProps {
@@ -20,6 +22,7 @@ interface CandidateCardProps {
 	pros?: string | null;
 	cons?: string | null;
 	rank?: number;
+	delta?: CandidateDelta;
 }
 
 export function CandidateCard({
@@ -38,6 +41,7 @@ export function CandidateCard({
 	pros,
 	cons,
 	rank,
+	delta,
 }: CandidateCardProps) {
 	const { weight, price } = useFormatters();
 	const openCandidateEditPanel = useUIStore((s) => s.openCandidateEditPanel);
@@ -165,11 +169,13 @@ export function CandidateCard({
 							{weight(weightGrams)}
 						</span>
 					)}
+					<ImpactDeltaBadge delta={delta} type="weight" formatFn={weight} />
 					{priceCents != null && (
 						<span className="inline-flex items-center px-2 py-0.5 rounded-full text-xs font-medium bg-green-50 text-green-500">
 							{price(priceCents)}
 						</span>
 					)}
+					<ImpactDeltaBadge delta={delta} type="price" formatFn={price} />
 					<span className="inline-flex items-center px-2 py-0.5 rounded-full text-xs font-medium bg-gray-50 text-gray-600">
 						<LucideIcon
 							name={categoryIcon}