feat(11-03): CPV-Filter + Wert-min/max-UI in Builder, DTO, FilterPanel

TenderQueryDto gains a validated cpv[] field (single-or-repeated query
param, normalized via @Transform); buildTenderWhere adds a cpvDivisions
hasSome branch (FILTER-03, Pitfall 2 — never an exact match against raw
cpvCodes). FilterPanel gets a CPV-Division autocomplete (search-by-label,
multi-select chips, repeated ?cpv= params) plus the previously
backend-only value filter's UI: valueMin/valueMax number inputs and an
"ohne Wertangabe einschließen" toggle (default on, matches the builder's
includeNullValue default from Plan 11-01) so the 91.6% NULL-value rows
stay visible by default. Verified against the live DB: cpv=45 matches all
three raw formats ("45", "45000000", "45000000-7") via the backfilled
cpvDivisions column.

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

apps/api/src/tenders/dto/tender-query.dto.ts

@@ -1,5 +1,6 @@
-import { Type } from 'class-transformer';
+import { Transform, Type } from 'class-transformer';
 import {
+  IsArray,
   IsBoolean,
   IsDate,
   IsIn,
@@ -24,8 +25,8 @@ import {
  *
  * Used for: GET /modules/tender-radar?page=1&limit=20&status=active&q=...
  *
- * CPV/favOnly filters are added in later Phase-11 plans (11-03/05) —
- * deliberately NOT added here.
+ * favOnly filter is added in a later Phase-11 plan (11-05) — deliberately
+ * NOT added here.
  */
 export class TenderQueryDto {
   /**
@@ -148,4 +149,21 @@ export class TenderQueryDto {
   @IsOptional()
   @IsString()
   bundesland?: string;
+
+  /**
+   * Ausgewählte CPV-Divisionen (FILTER-03, D-03) — matched against the
+   * normalizer/backfill-derived `cpvDivisions` column via `hasSome` in the
+   * builder (Pitfall 2: never an exact match against raw cpvCodes).
+   * Normalizes a single-value query string (`?cpv=45`) to a one-element
+   * array — Express's default query parser only produces an array when the
+   * key is repeated (`?cpv=45&cpv=71`), so a lone selection would otherwise
+   * fail @IsArray validation.
+   */
+  @IsOptional()
+  @Transform(({ value }) =>
+    value === undefined ? value : Array.isArray(value) ? value : [value],
+  )
+  @IsArray()
+  @IsString({ each: true })
+  cpv?: string[];
 }