- Add `numbers` store module with `list` and `update` methods backed by
the `numbers` table (prefix, padding, next) per company.
- Add sql queries LIST_BY_COMPANY, GET_BY_COMPANY_AND_ID, UPDATE_...
- Regenerate and wire API docs for `numbers`.
companysetting:
- Remove the `delete` endpoint (settings are now upsert/read only).
- Restrict `set` to a fixed allow-list of keys:
ui.theme, keys.tavily, keys.openrouter, labelprinter.addr, labelprinter.type.
- Drop DELETE_BY_COMPANY_AND_KEY sql and the delete store file.
Docs: update README, API.md, API.companysetting.md, API.numbers.md.
brand now carries a NOT NULL company_id (unique per (company_id, name))
with brand.list/upsert/delete backed by resolveCompanyAccess. Adds
companysetting key-value store (list/get/set/delete, frontend flag).
