feat(01-02): implement item, category, and totals service layers

- Item CRUD: getAllItems with category join, getById, create, update, delete
- Category CRUD: getAll ordered by name, create, update, delete with reassignment
- Totals: per-category aggregates and global totals via SQL SUM/COUNT
- All 20 service tests passing

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/server/services/item.service.ts

@@ -0,0 +1,112 @@
+import { eq, sql } from "drizzle-orm";
+import { items, categories } from "../../db/schema.ts";
+import { db as prodDb } from "../../db/index.ts";
+import type { CreateItem } from "../../shared/types.ts";
+
+type Db = typeof prodDb;
+
+export function getAllItems(db: Db = prodDb) {
+  return db
+    .select({
+      id: items.id,
+      name: items.name,
+      weightGrams: items.weightGrams,
+      priceCents: items.priceCents,
+      categoryId: items.categoryId,
+      notes: items.notes,
+      productUrl: items.productUrl,
+      imageFilename: items.imageFilename,
+      createdAt: items.createdAt,
+      updatedAt: items.updatedAt,
+      categoryName: categories.name,
+      categoryEmoji: categories.emoji,
+    })
+    .from(items)
+    .innerJoin(categories, eq(items.categoryId, categories.id))
+    .all();
+}
+
+export function getItemById(db: Db = prodDb, id: number) {
+  return (
+    db
+      .select({
+        id: items.id,
+        name: items.name,
+        weightGrams: items.weightGrams,
+        priceCents: items.priceCents,
+        categoryId: items.categoryId,
+        notes: items.notes,
+        productUrl: items.productUrl,
+        imageFilename: items.imageFilename,
+        createdAt: items.createdAt,
+        updatedAt: items.updatedAt,
+      })
+      .from(items)
+      .where(eq(items.id, id))
+      .get() ?? null
+  );
+}
+
+export function createItem(
+  db: Db = prodDb,
+  data: Partial<CreateItem> & { name: string; categoryId: number; imageFilename?: string },
+) {
+  return db
+    .insert(items)
+    .values({
+      name: data.name,
+      weightGrams: data.weightGrams ?? null,
+      priceCents: data.priceCents ?? null,
+      categoryId: data.categoryId,
+      notes: data.notes ?? null,
+      productUrl: data.productUrl ?? null,
+      imageFilename: data.imageFilename ?? null,
+    })
+    .returning()
+    .get();
+}
+
+export function updateItem(
+  db: Db = prodDb,
+  id: number,
+  data: Partial<{
+    name: string;
+    weightGrams: number;
+    priceCents: number;
+    categoryId: number;
+    notes: string;
+    productUrl: string;
+    imageFilename: string;
+  }>,
+) {
+  // Check if item exists first
+  const existing = db
+    .select({ id: items.id })
+    .from(items)
+    .where(eq(items.id, id))
+    .get();
+
+  if (!existing) return null;
+
+  return db
+    .update(items)
+    .set({ ...data, updatedAt: new Date() })
+    .where(eq(items.id, id))
+    .returning()
+    .get();
+}
+
+export function deleteItem(db: Db = prodDb, id: number) {
+  // Get item first (for image cleanup info)
+  const item = db
+    .select()
+    .from(items)
+    .where(eq(items.id, id))
+    .get();
+
+  if (!item) return null;
+
+  db.delete(items).where(eq(items.id, id)).run();
+
+  return item;
+}