chore: PostgreSQL migration compatibility and infrastructure improvements

Database & Migrations:
- Update all Alembic migrations for PostgreSQL compatibility
- Remove SQLite-specific syntax (AUTOINCREMENT, etc.)
- Add database utility helpers for PostgreSQL operations
- Fix services to use PostgreSQL-compatible queries

Documentation:
- Add comprehensive Docker deployment guide
- Add production deployment documentation
- Add infrastructure architecture documentation
- Update database setup guide for PostgreSQL-only
- Expand troubleshooting guide

Architecture & Validation:
- Add migration.yaml rules for SQL compatibility checking
- Enhance validate_architecture.py with migration validation
- Update architecture rules to validate Alembic migrations

Development:
- Fix duplicate install-all target in Makefile
- Add Celery/Redis validation to install.py script
- Add docker-compose.test.yml for CI testing
- Add squash_migrations.py utility script
- Update tests for PostgreSQL compatibility
- Improve test fixtures in conftest.py

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

tests/unit/services/test_onboarding_service.py

@@ -218,17 +218,13 @@ class TestOnboardingServiceStep1:
 
         service = OnboardingService(db)
 
-        # First create the onboarding record
-        onboarding = VendorOnboarding(
-            vendor_id=99999,
-            status=OnboardingStatus.NOT_STARTED.value,
-        )
-        db.add(onboarding)
-        db.flush()
+        # Use a vendor_id that doesn't exist
+        # The service should check vendor exists before doing anything
+        non_existent_vendor_id = 999999
 
         with pytest.raises(VendorNotFoundException):
             service.complete_company_profile(
-                vendor_id=99999,
+                vendor_id=non_existent_vendor_id,
                 default_language="en",
                 dashboard_language="en",
             )