feat(127): erli integration foundation

Phase 127 complete:

- add global Erli settings schema and encrypted API key repository

- add real read-only Erli API connection test and settings UI

- expose Erli in integrations hub and update PAUL/docs state

DOCS/DB_SCHEMA.md

@@ -1,6 +1,6 @@
 # Database Schema
 
-**Updated:** 2026-05-12 | **Total tables:** 62 | **Engine:** InnoDB | **Charset:** utf8mb4_unicode_ci
+**Updated:** 2026-05-15 | **Total tables:** 63 | **Engine:** InnoDB | **Charset:** utf8mb4_unicode_ci
 
 ---
 
@@ -613,6 +613,20 @@ UNIQUE: `(integration_id)` - one global SMSPLANET settings row.
 
 ---
 
+**erli_integration_settings** - Erli marketplace API credentials (Phase 127; fixed 1 row)
+| Column | Type | Nullable | Notes |
+|--------|------|----------|-------|
+| `id` | TINYINT UNSIGNED | NO | PK, always 1 |
+| `integration_id` | INT UNSIGNED | YES | UNIQUE, FK -> integrations(id) CASCADE; single `integrations.type='erli'` row |
+| `api_key_encrypted` | TEXT | YES | AES-encrypted Bearer API key via `IntegrationSecretCipher` |
+| `account_label` | VARCHAR(128) | YES | Optional display label for the integrations hub |
+| `created_at` | DATETIME | NO | DEFAULT CURRENT_TIMESTAMP |
+| `updated_at` | DATETIME | NO | DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP |
+
+UNIQUE: `(integration_id)` - one global Erli settings row. Base integration uses `base_url='https://erli.pl/svc/shop-api'`. Phase 127 only stores configuration and test results; order import, status sync, shipments and tracking are deferred to later v3.8 phases.
+
+---
+
 **sms_messages** - SMSPLANET inbound/outbound conversation history (Phase 121)
 | Column | Type | Nullable | Notes |
 |--------|------|----------|-------|