feat(38-01): admin tag routes + route registration + integration tests

- Create admin-tags.ts with GET list, GET single, POST, PUT (cycle guard → 400), DELETE
- Register /tags route in admin.ts
- Add 13-test integration suite covering CRUD, cycle detection, orphan behavior

src/server/routes/admin-tags.ts

@@ -0,0 +1,80 @@
+import { zValidator } from "@hono/zod-validator";
+import { Hono } from "hono";
+import { z } from "zod";
+import { parseId } from "../lib/params.ts";
+import {
+	createTag,
+	deleteTag,
+	getAdminTags,
+	getTagWithCounts,
+	updateTag,
+} from "../services/tag.service.ts";
+
+type Env = { Variables: { db?: any; userId?: number } };
+
+const app = new Hono<Env>();
+
+const createTagSchema = z.object({
+	name: z.string().min(1),
+	parentId: z.number().int().positive().nullable().optional(),
+});
+
+const updateTagSchema = z.object({
+	name: z.string().min(1).optional(),
+	parentId: z.number().int().positive().nullable().optional(),
+});
+
+// GET /api/admin/tags — list all tags with parentId and itemCount
+app.get("/", async (c) => {
+	const db = c.get("db");
+	const result = await getAdminTags(db);
+	return c.json(result);
+});
+
+// GET /api/admin/tags/:id — single tag with counts
+app.get("/:id", async (c) => {
+	const db = c.get("db");
+	const id = parseId(c.req.param("id"));
+	if (!id) return c.json({ error: "Invalid tag ID" }, 400);
+	const tag = await getTagWithCounts(db, id);
+	if (!tag) return c.json({ error: "Tag not found" }, 404);
+	return c.json(tag);
+});
+
+// POST /api/admin/tags — create a new tag
+app.post("/", zValidator("json", createTagSchema), async (c) => {
+	const db = c.get("db");
+	const data = c.req.valid("json");
+	const tag = await createTag(db, data);
+	return c.json(tag, 201);
+});
+
+// PUT /api/admin/tags/:id — rename and/or reparent a tag
+app.put("/:id", zValidator("json", updateTagSchema), async (c) => {
+	const db = c.get("db");
+	const id = parseId(c.req.param("id"));
+	if (!id) return c.json({ error: "Invalid tag ID" }, 400);
+	const data = c.req.valid("json");
+	try {
+		const tag = await updateTag(db, id, data);
+		if (!tag) return c.json({ error: "Tag not found" }, 404);
+		return c.json(tag);
+	} catch (err) {
+		if (err instanceof Error && err.message.startsWith("Cycle detected")) {
+			return c.json({ error: err.message }, 400);
+		}
+		throw err;
+	}
+});
+
+// DELETE /api/admin/tags/:id — remove tag (children become top-level via ON DELETE SET NULL)
+app.delete("/:id", async (c) => {
+	const db = c.get("db");
+	const id = parseId(c.req.param("id"));
+	if (!id) return c.json({ error: "Invalid tag ID" }, 400);
+	const deleted = await deleteTag(db, id);
+	if (!deleted) return c.json({ error: "Tag not found" }, 404);
+	return c.json({ success: true });
+});
+
+export { app as adminTagRoutes };

src/server/routes/admin.ts

@@ -1,6 +1,7 @@
 import { Hono } from "hono";
 import { requireAdmin, requireAuth } from "../middleware/auth.ts";
 import { adminItemRoutes } from "./admin-items.ts";
+import { adminTagRoutes } from "./admin-tags.ts";
 
 type Env = { Variables: { db?: any; userId?: number } };
 
@@ -17,4 +18,7 @@ app.get("/", async (c) => {
 // Admin item management
 app.route("/items", adminItemRoutes);
 
+// Admin tag management
+app.route("/tags", adminTagRoutes);
+
 export { app as adminRoutes };