feat(stammdaten): crud fuer hersteller, themen und standorte

Gemeinsame CrudSection fuer die drei kleinen Stammdatentabellen; sie
unterscheiden sich nur in den Formularfeldern. Loeschen ist bewusst
blockiert, solange Sets am Hersteller oder Thema haengen - Standorte
duerfen weg, die Sammlungseintraege verlieren dann nur den Ort.

Dazu die gemeinsamen Bausteine: zod-Schemata fuer alle Formulare,
einheitliches ActionResult, Slug-Erzeugung mit deutschen Umlauten,
Geld als Cent und Datumsformatierung dd.MM.yyyy.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

src/lib/queries/master-data.ts

@@ -0,0 +1,71 @@
+import 'server-only';
+import { asc, count, eq, sql } from 'drizzle-orm';
+import { db } from '@/db';
+import { location, manufacturer, set, theme } from '@/db/schema';
+
+export function listManufacturers() {
+  return db
+    .select({
+      id: manufacturer.id,
+      name: manufacturer.name,
+      slug: manufacturer.slug,
+      website: manufacturer.website,
+      setCount: count(set.id),
+    })
+    .from(manufacturer)
+    .leftJoin(set, eq(set.manufacturerId, manufacturer.id))
+    .groupBy(manufacturer.id)
+    .orderBy(asc(manufacturer.name))
+    .all();
+}
+
+export function listThemes() {
+  const parent = sql<string | null>`(
+    select parent.name from theme as parent where parent.id = ${theme.parentThemeId}
+  )`.as('parent_name');
+
+  return db
+    .select({
+      id: theme.id,
+      name: theme.name,
+      manufacturerId: theme.manufacturerId,
+      manufacturerName: manufacturer.name,
+      parentThemeId: theme.parentThemeId,
+      parentName: parent,
+    })
+    .from(theme)
+    .innerJoin(manufacturer, eq(manufacturer.id, theme.manufacturerId))
+    .orderBy(asc(manufacturer.name), asc(theme.name))
+    .all();
+}
+
+/** Themes of one manufacturer - used by the set form and the catalog filter. */
+export function listThemesByManufacturer(manufacturerId: string) {
+  return db
+    .select({ id: theme.id, name: theme.name })
+    .from(theme)
+    .where(eq(theme.manufacturerId, manufacturerId))
+    .orderBy(asc(theme.name))
+    .all();
+}
+
+export function listLocations() {
+  const parent = sql<string | null>`(
+    select parent.name from location as parent where parent.id = ${location.parentLocationId}
+  )`.as('parent_name');
+
+  return db
+    .select({
+      id: location.id,
+      name: location.name,
+      parentLocationId: location.parentLocationId,
+      parentName: parent,
+    })
+    .from(location)
+    .orderBy(asc(location.name))
+    .all();
+}
+
+export type ManufacturerListRow = ReturnType<typeof listManufacturers>[number];
+export type ThemeListRow = ReturnType<typeof listThemes>[number];
+export type LocationListRow = ReturnType<typeof listLocations>[number];