refactor(scheduling): shared types, structured reason, cross-region candidates

- Extract shared types to src/shared/scheduling/types.ts (client/server both re-export)
- Convert SchedulingSuggestion.reason from string to structured { lines, conclusion }
- Remove hard region filter; algorithm keeps cross-region candidates with isSameRegion flag
- SuggestionDetail renders same-region vs cross-region sections with a divider
- Close detail modal when selected suggestion no longer exists in data
- Unify estimatedGain definition (strict canQualifyAfterSwap) between algorithm and API layers

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/shared/scheduling/types.ts

@@ -0,0 +1,83 @@
+// Shared scheduling types — used by both client (modules/scheduling) and server
+// (server/routes/scheduling). Keep server-only types (EnrichedVehicle etc.) in
+// server/routes/scheduling/types.ts.
+
+export interface SchedulingVehicleInfo {
+  plateNumber: string;
+  targetId: number;
+  targetName: string;
+  vehicleType: string;
+  totalMileage: number;
+  currentYearMileage: number;
+  completionRate: number;
+  yearTarget: number;
+  region: string;
+  province: string;
+  customer: string | null;
+  department: string | null;
+  manager: string | null;
+  customerAvgDaily: number;
+  predictedYearEnd: number;
+  daysLeft: number;
+}
+
+export interface CandidateVehicle {
+  plateNumber: string;
+  targetId: number | null;
+  targetName: string | null;
+  vehicleType: string;
+  totalMileage: number;
+  completionRate: number;
+  yearTarget: number | null;
+  daysLeft: number;
+  region: string;
+  province: string;
+  mileageGap: number;
+  predictedAfterSwap: number;
+  canQualifyAfterSwap: boolean;
+  isSameRegion: boolean;
+}
+
+export interface ReasonLine {
+  label: string;
+  value: string;
+}
+
+export interface ReasonBlock {
+  lines: ReasonLine[];
+  conclusion: string;
+}
+
+export interface SchedulingSuggestion {
+  id: string;
+  priority: 'high' | 'medium';
+  type: 'replace_qualified' | 'rescue_hopeless';
+  currentVehicle: SchedulingVehicleInfo;
+  candidates: CandidateVehicle[];
+  reason: ReasonBlock;
+}
+
+export interface SchedulingSummary {
+  qualifiedCount: number;
+  hopelessCount: number;
+  suggestionCount: number;
+  estimatedGain: number;
+}
+
+export interface SchedulingTargetOption {
+  id: number;
+  name: string;
+  vehicleCount: number;
+}
+
+export interface SchedulingResponse {
+  summary: SchedulingSummary;
+  suggestions: SchedulingSuggestion[];
+  targets: SchedulingTargetOption[];
+}
+
+export interface NotifyRequest {
+  suggestionId: string;
+  currentPlate: string;
+  candidatePlate: string;
+}