feat: add MCP tool handlers, definitions, and collection resource

Wrap existing service layer with MCP-compatible tool handlers for items,
categories, threads/candidates, setups, and image fetching. Add collection
summary resource for overview data. All 14 MCP-specific tests passing.

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

src/server/mcp/resources/collection.ts

@@ -0,0 +1,41 @@
+import type { db as prodDb } from "@/db/index.ts";
+import { getAllCategories } from "../../services/category.service.ts";
+import { getAllItems } from "../../services/item.service.ts";
+import { getAllSetups } from "../../services/setup.service.ts";
+import { getAllThreads } from "../../services/thread.service.ts";
+import { getGlobalTotals } from "../../services/totals.service.ts";
+
+type Db = typeof prodDb;
+
+export function getCollectionSummary(db: Db) {
+	const totals = getGlobalTotals(db);
+	const categories = getAllCategories(db);
+	const items = getAllItems(db);
+	const setups = getAllSetups(db);
+	const activeThreads = getAllThreads(db, false);
+
+	// Build items-by-category map
+	const itemsByCategory: Record<string, number> = {};
+	for (const item of items) {
+		const catName = item.categoryName;
+		itemsByCategory[catName] = (itemsByCategory[catName] ?? 0) + 1;
+	}
+
+	return {
+		overview: {
+			totalItems: totals?.itemCount ?? 0,
+			totalWeightGrams: totals?.totalWeight ?? 0,
+			totalCostCents: totals?.totalCost ?? 0,
+			categoryCount: categories.length,
+			setupCount: setups.length,
+			activeThreadCount: activeThreads.length,
+		},
+		itemsByCategory,
+		activeThreads: activeThreads.map((t) => ({
+			id: t.id,
+			name: t.name,
+			candidateCount: t.candidateCount,
+			category: t.categoryName,
+		})),
+	};
+}