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/contact/list.md

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+# `GET /entity/{entityId}/contact`
+
+Protected. Requires a valid session cookie (`credentials: 'include'`).
+
+List entity contacts
+
+Lists contacts for an entity of the selected company (`contactType` e.g. `email`, `phone`).
+
+## Path parameters
+
+| Param | Required | Type | Description |
+|-------|----------|------|-------------|
+| `entityId` | yes | integer |  |
+
+## Response `200`
+
+Contact list
+
+```json
+{
+  "contacts": [
+    {
+      "id": 1,
+      "entityId": 1,
+      "contactType": "…",
+      "contact": "…"
+    }
+  ]
+}
+```
+
+## Errors
+
+| Status | Description |
+|--------|-------------|
+| 400 | No company selected or invalid entityId — `{"error":"…"}` |
+| 401 | Unauthorized — `{"error":"…"}` |
+| 403 | Not authorized — `{"error":"…"}` |
+| 404 | Entity or company not found — `{"error":"…"}` |
+
+---
+
+_Generated from `@openapi` JSDoc. Do not edit by hand — run `npm run docs:api`._