Initial settings service

Fastify API for storing third-party integration credentials (Newbook, Resos,
Nextcloud, Azure, SambaPOS) with AES-256-GCM encryption for sensitive fields.
Includes Newbook room sync endpoint and global_config store for shared app data.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/integrations/schema.js

@@ -0,0 +1,32 @@
+// Field definitions per integration.
+// configFields  — stored plaintext in the config JSONB column
+// secretFields  — encrypted in the secrets column (api keys, passwords)
+export const INTEGRATIONS = {
+  newbook: {
+    name: 'Newbook PMS',
+    configFields: ['region', 'username'],
+    secretFields: ['api_key', 'password'],
+  },
+  resos: {
+    name: 'Resos Reservations',
+    configFields: [],
+    secretFields: ['api_key'],
+  },
+  nextcloud: {
+    name: 'Nextcloud',
+    configFields: ['base_url', 'username'],
+    secretFields: ['password'],
+  },
+  azure: {
+    name: 'Azure AD',
+    configFields: ['tenant_id', 'client_id'],
+    secretFields: ['client_secret'],
+  },
+  sambapos: {
+    name: 'SambaPOS',
+    configFields: ['host', 'port', 'database', 'graphql_endpoint', 'username'],
+    secretFields: ['password'],
+  },
+}
+
+export const MASKED = '••••••••'