Add customergroup and entity HTTP APIs with address and contact routes.

Expose store-backed CRUD for customer groups, entities, nested addresses, and contacts, matching the documented dashdbschema contracts.

docs/api/routes/entity/list.md

@@ -0,0 +1,47 @@
+# `GET /entity`
+
+Protected. Requires a valid session cookie (`credentials: 'include'`).
+
+List entities
+
+Lists entities for the selected company. Optional `customergroupId`
+query filters to one group (must belong to the company).
+
+
+## Query parameters
+
+| Param | Required | Type | Description |
+|-------|----------|------|-------------|
+| `customergroupId` | no | integer |  |
+
+## Response `200`
+
+Entity list
+
+```json
+{
+  "entities": [
+    {
+      "id": 1,
+      "customergroupId": 1,
+      "firstName": "…",
+      "name": "…",
+      "createdAt": "2026-08-10T00:00:00.000Z",
+      "updatedAt": "2026-08-10T00:00:00.000Z"
+    }
+  ]
+}
+```
+
+## Errors
+
+| Status | Description |
+|--------|-------------|
+| 400 | No company selected or invalid customergroupId — `{"error":"…"}` |
+| 401 | Unauthorized — `{"error":"…"}` |
+| 403 | Not authorized — `{"error":"…"}` |
+| 404 | Company or customer group not found — `{"error":"…"}` |
+
+---
+
+_Generated from `@openapi` JSDoc. Do not edit by hand — run `npm run docs:api`._