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/lib/version.ts

@@ -1,2 +1,2 @@
 // Bump on every user-visible release. Changelog entries live in `src/lib/changelog.ts`.
-export const APP_VERSION = "0.15.0";
+export const APP_VERSION = "0.16.0";