feat: add CSV import/export for gear collection

Adds export (GET /api/items/export) and import (POST /api/items/import) routes
backed by a pure csv.service with no external deps, plus useExportItems/useImportItems
hooks and an Import/Export section in the Settings page.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/server/routes/items.ts

@@ -4,6 +4,7 @@ import { zValidator } from "@hono/zod-validator";
 import { Hono } from "hono";
 import { createItemSchema, updateItemSchema } from "../../shared/schemas.ts";
 import { parseId } from "../lib/params.ts";
+import { exportItemsCsv, importItemsCsv } from "../services/csv.service.ts";
 import {
 	createItem,
 	deleteItem,
@@ -17,6 +18,27 @@ type Env = { Variables: { db?: any } };
 
 const app = new Hono<Env>();
 
+app.get("/export", (c) => {
+	const db = c.get("db");
+	const csv = exportItemsCsv(db);
+	c.header("Content-Type", "text/csv");
+	c.header("Content-Disposition", 'attachment; filename="gearbox-export.csv"');
+	return c.body(csv);
+});
+
+app.post("/import", async (c) => {
+	const db = c.get("db");
+	const body = await c.req.parseBody();
+	// Accept either "file" (direct) or "image" (via apiUpload helper)
+	const file = body.file ?? body.image;
+	if (!file || typeof file === "string") {
+		return c.json({ error: "No CSV file provided" }, 400);
+	}
+	const content = await file.text();
+	const result = importItemsCsv(db, content);
+	return c.json(result);
+});
+
 app.get("/", (c) => {
 	const db = c.get("db");
 	const items = getAllItems(db);