v0.16.0 — HomeBox CSV import + sold lifecycle + custom fields

Bring an existing HomeBox inventory straight in, and capture the fields HomeBox
has that we were missing (skipping asset IDs per Tony).

- Item: soldTo/soldPrice/soldDate/soldNotes + flexible customFields (JSON, e.g.
  VIN / oil weight for vehicles); both editable in the item dialog and shown on
  the detail page
- Pure HomeBox CSV parser (src/lib/inventory/homebox-import.ts, +5 tests) —
  RFC4180 quoting (commas/newlines/escaped quotes in fields), HomeBox's 0001-*
  null dates and 0 = empty price, semicolon labels, HB.field.* custom columns,
  nested 'A / B' location paths
- Import service + /api/v1/items/import: find-or-creates the nested locations
  and labels, creates items, recomputes location paths, returns a summary
- Inventory 'Import' button: paste/upload CSV, review every row with checkboxes
  (uncheck to skip), then import. Preview parses client-side (parser is pure)
- Verified end-to-end: nested locations, split labels, sold + custom fields,
  skip, quoted names, null-date handling. tsc + 38 tests + build green

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/app/api/v1/items/import/route.ts

@@ -0,0 +1,22 @@
+import { NextResponse } from "next/server";
+import { z } from "zod";
+import { authenticateRequest, handleApiError } from "@/lib/api/authenticate";
+import { importHomeBoxItems } from "@/lib/services/inventory-import";
+
+const schema = z.object({
+  csv: z.string().min(1),
+  skip: z.array(z.string()).optional(),
+});
+
+// POST /api/v1/items/import — import a HomeBox CSV export. `skip` lists item
+// names to leave out (e.g. the ones unchecked in the preview).
+export async function POST(req: Request) {
+  try {
+    const ctx = await authenticateRequest(req, "items:write");
+    const { csv, skip } = schema.parse(await req.json());
+    const summary = await importHomeBoxItems(ctx, { csv, skip });
+    return NextResponse.json(summary, { status: 201 });
+  } catch (err) {
+    return handleApiError(err);
+  }
+}