feat(19-03): add tag filtering to global item search and migrate owner count

- searchGlobalItems now accepts tagNames param with AND intersection logic
- Owner count uses items.globalItemId instead of removed itemGlobalLinks
- Removed linkItemToGlobal and unlinkItemFromGlobal functions
- Route handlers now async with tags query param support
- Rewrote tests to async PGlite pattern, added tag filtering tests

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

src/server/routes/global-items.ts

@@ -9,21 +9,26 @@ type Env = { Variables: { db?: any } };
 
 const app = new Hono<Env>();
 
-app.get("/", (c) => {
+app.get("/", async (c) => {
 	const db = c.get("db");
 	const q = c.req.query("q");
-	const items = searchGlobalItems(db, q || undefined);
+	const tagsParam = c.req.query("tags");
+	const tagNames = tagsParam
+		? tagsParam
+				.split(",")
+				.map((t) => t.trim())
+				.filter(Boolean)
+		: undefined;
+	const items = await searchGlobalItems(db, q || undefined, tagNames);
 	return c.json(items);
 });
 
-app.get("/:id", (c) => {
+app.get("/:id", async (c) => {
 	const db = c.get("db");
 	const id = parseId(c.req.param("id"));
 	if (!id) return c.json({ error: "Invalid global item ID" }, 400);
-
-	const item = getGlobalItemWithOwnerCount(db, id);
+	const item = await getGlobalItemWithOwnerCount(db, id);
 	if (!item) return c.json({ error: "Global item not found" }, 404);
-
 	return c.json(item);
 });