feat: add scenario analysis workspace

apps/web/src/lib/api.ts

@@ -415,6 +415,59 @@ export type SimilarNeighborhoodResponse = {
   items: SimilarNeighborhood[];
 };
 
+export type ScenarioRun = {
+  scenario_run_id: number;
+  name: string;
+  target_month: string;
+  area_id: string | null;
+  interest_rate_delta_bps: number;
+  policy_signal_delta: number;
+  supply_delta_pct: number;
+  rent_delta_pct: number;
+  notes: string;
+  created_at: string;
+};
+
+export type CreateScenarioRun = {
+  name: string;
+  target_month: string;
+  area_id?: string;
+  interest_rate_delta_bps: number;
+  policy_signal_delta: number;
+  supply_delta_pct: number;
+  rent_delta_pct: number;
+  notes?: string;
+};
+
+export type ScenarioAreaResult = {
+  area_id: string;
+  name: string;
+  district: string;
+  baseline_score: number;
+  projected_score: number;
+  score_delta: number;
+  baseline_price_psm: number;
+  projected_price_psm: number;
+  price_delta_pct: number;
+  projected_rent_yield_pct: number;
+  projected_liquidity_score: number;
+  projected_supply_risk_score: number;
+  recommendation: string;
+  risk_notes: string[];
+};
+
+export type ScenarioVariant = {
+  key: string;
+  name: string;
+  assumptions: string[];
+  items: ScenarioAreaResult[];
+};
+
+export type ScenarioRunResponse = {
+  run: ScenarioRun;
+  variants: ScenarioVariant[];
+};
+
 export type ComparisonMetricValue = {
   id: string;
   value: number | null;
@@ -663,6 +716,29 @@ export async function fetchAreaScoreLineage(
   );
 }
 
+export async function fetchScenarioRuns(filters: {
+  target_month?: string;
+  area_id?: string;
+} = {}): Promise<ScenarioRun[]> {
+  const params = new URLSearchParams();
+  for (const [key, value] of Object.entries(filters)) {
+    if (value) {
+      params.set(key, value);
+    }
+  }
+  const query = params.toString();
+  return fetchJson(`/api/v1/scenario-runs${query ? `?${query}` : ""}`);
+}
+
+export async function createScenarioRun(
+  payload: CreateScenarioRun,
+): Promise<ScenarioRunResponse> {
+  return fetchJson("/api/v1/scenario-runs", {
+    method: "POST",
+    body: JSON.stringify(payload),
+  });
+}
+
 async function fetchJson<T>(path: string, init?: RequestInit): Promise<T> {
   const response = await fetch(`${API_BASE_URL}${path}`, {
     ...init,