feat(11-06): TenderSavedSearch model + CRUD service (FILTER-06)

GREEN phase — adds TenderSavedSearch (userId+tenantId scoped, filters
Json, @@unique([userId,name])), the migration (applied to local dev DB),
and TenderSavedSearchService following the FavoritesService/
TenderTriageService pattern: manual where:{userId} scoping (no
forTenant()/RLS), ownership check before update/remove, P2002 unique
conflicts translated to ConflictException.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/api/src/tenders/dto/saved-search.dto.ts

@@ -0,0 +1,41 @@
+import { IsNotEmpty, IsObject, IsOptional, IsString, MaxLength } from 'class-validator';
+
+/**
+ * Body DTO for POST /modules/tender-radar/saved-searches (FILTER-06).
+ *
+ * Security (T-11-14 / V4 — IDOR): deliberately has NO userId or tenantId
+ * field — both are always derived server-side from the auth context
+ * (FavoritesController.extractContext pattern) in TendersController, never
+ * trusted from the request body.
+ *
+ * `filters` is validated only as a plain object (T-11-17 / V5) — its shape
+ * mirrors the FilterPanel's URL-searchParams contract on the frontend, but
+ * the backend does not re-validate individual filter keys here; Prisma
+ * stores it as parametrized JSONB (no string interpolation, V5).
+ */
+export class CreateSavedSearchDto {
+  @IsString()
+  @IsNotEmpty()
+  @MaxLength(100)
+  name!: string;
+
+  @IsObject()
+  filters!: Record<string, unknown>;
+}
+
+/**
+ * Body DTO for PATCH /modules/tender-radar/saved-searches/:searchId.
+ * Both fields optional — only provided fields are updated (FavoritesService
+ * UpdateFavoriteDto pattern).
+ */
+export class UpdateSavedSearchDto {
+  @IsOptional()
+  @IsString()
+  @IsNotEmpty()
+  @MaxLength(100)
+  name?: string;
+
+  @IsOptional()
+  @IsObject()
+  filters?: Record<string, unknown>;
+}