feat: add Docker deployment, web installer, and local test environment

- Multi-stage Dockerfiles for API (NestJS) and Web (Next.js standalone)
- docker-compose.prod.yml: full production stack (postgres, redis, keycloak,
  api, web) with optional Caddy/Let's Encrypt via --profile ssl
- docker-compose.local.yml: identical local test stack, all ports exposed
- docker/postgres/init.sql: auto-creates tos_app DB on first start
- Caddyfile: reverse proxy for app domain + auth subdomain
- install.sh: interactive installer (domain, SSL mode, secret generation)
- NestJS SetupModule: @Public() endpoints for /setup/status, /setup/admin,
  /setup/branding, /setup/complete with setup-token guard
- Web installer: 4-step flow (system check, admin creation, branding, complete)
  at /[locale]/setup/* with public middleware bypass
- i18n: installer namespace added to de.json and en.json
- CORS: x-setup-token header allowed in main.ts

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

apps/api/src/app.module.ts

@@ -31,6 +31,9 @@ import { HrModule } from './modules/hr/hr.module';
 // Phase 6 modules - Integrations
 import { IntegrationsModule } from './modules/integrations/integrations.module';
 
+// Setup module - initial system configuration wizard
+import { SetupModule } from './modules/setup/setup.module';
+
 @Module({
   imports: [
     // Configuration
@@ -75,6 +78,9 @@ import { IntegrationsModule } from './modules/integrations/integrations.module';
 
     // Phase 6 modules - Integrations
     IntegrationsModule,
+
+    // Setup wizard - initial system configuration
+    SetupModule,
   ],
   providers: [
     // Global JWT Guard - routes are protected by default