Add company settings and number sequence API routes

- Add CompanySetting routes (list, get, set) backed by company-scoped store
- Add Number routes (list, update) for managing number sequences
- Register new store namespaces for numbers and companysetting
- Add CompanySetting and NumberSequence schemas to OpenAPI
- Regenerate API docs and index for the new routes

docs/api/routes/companysetting/get.md

@@ -0,0 +1,41 @@
+# `GET /company/setting/{key}`
+
+Protected. Requires a valid session cookie (`credentials: 'include'`).
+
+Get company setting by key
+
+Returns a single company setting for the authenticated user's selected
+company, or `404` if it does not exist.
+
+
+## Path parameters
+
+| Param | Required | Type | Description |
+|-------|----------|------|-------------|
+| `key` | yes | string |  |
+
+## Response `200`
+
+Company setting
+
+```json
+{
+  "setting": {
+    "key": "…",
+    "value": "…"
+  }
+}
+```
+
+## Errors
+
+| Status | Description |
+|--------|-------------|
+| 400 | No company selected — `{"error":"…"}` |
+| 401 | Unauthorized — `{"error":"…"}` |
+| 403 | Not authorized — `{"error":"…"}` |
+| 404 | Company setting or company not found — `{"error":"…"}` |
+
+---
+
+_Generated from `@openapi` JSDoc. Do not edit by hand — run `npm run docs:api`._