feat(116): hostedsms integration settings

Phase 116 complete:
- add HostedSMS settings with encrypted password storage
- add SimpleAPI real test SMS flow and integrations hub row
- document schema, architecture, changelog, and PAUL state

Co-Authored-By: Codex <noreply@openai.com>

DOCS/DB_SCHEMA.md

@@ -558,6 +558,22 @@ UNIQUE: `(type, name)`
 
 ---
 
+**hostedsms_integration_settings** - HostedSMS account credentials (Phase 116; fixed 1 row)
+| Column | Type | Nullable | Notes |
+|--------|------|----------|-------|
+| `id` | TINYINT UNSIGNED | NO | PK, always 1 |
+| `integration_id` | INT UNSIGNED | YES | UNIQUE, FK -> integrations(id) CASCADE |
+| `user_email` | VARCHAR(190) | YES | HostedSMS login |
+| `password_encrypted` | TEXT | YES | AES-encrypted via `IntegrationSecretCipher` |
+| `sender` | VARCHAR(32) | YES | HostedSMS sender name / nadpis |
+| `convert_message_to_gsm7` | TINYINT(1) | NO | DEFAULT 0 |
+| `created_at` | DATETIME | NO | |
+| `updated_at` | DATETIME | NO | |
+
+UNIQUE: `(integration_id)` - one global HostedSMS settings row.
+
+---
+
 ## Accounting / Receipts
 
 **receipt_configs** — Receipt generation configurations