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>

alembic/versions/g5b6c7d8e9f0_add_scan_status_fields.py

@@ -62,12 +62,12 @@ def upgrade() -> None:
     )
 
     # Update existing records to have proper started_at and completed_at
-    # This is done via raw SQL for efficiency
+    # This is done via raw SQL for efficiency (PostgreSQL syntax)
     op.execute(
         """
         UPDATE architecture_scans
         SET started_at = timestamp,
-            completed_at = datetime(timestamp, '+' || CAST(duration_seconds AS TEXT) || ' seconds')
+            completed_at = timestamp + (COALESCE(duration_seconds, 0) || ' seconds')::interval
         WHERE started_at IS NULL
         """
     )