feat: integrate First8 Marketing hyper-personalization system

Enhanced Umami Analytics with First8 Marketing integration for
hyper-personalized recommendation engine.

Database Enhancements:
- PostgreSQL 17 with Apache AGE 1.6.0 (graph database)
- TimescaleDB 2.23.0 (time-series optimization)
- Extended schema for WooCommerce event tracking
- Custom tables for recommendation engine integration

Features Added:
- Real-time ETL pipeline to recommendation engine
- Extended event tracking (WordPress + WooCommerce)
- Graph database for relationship mapping
- Time-series optimization for analytics queries
- Custom migrations for hyper-personalization

Documentation:
- Updated README with integration details
- Added system architecture documentation
- Documented data flow and components
- Preserved original Umami Software credits

Integration Components:
- First8 Marketing Track plugin (event tracking)
- Recommendation Engine (ML backend)
- First8 Marketing Recommendation Engine plugin (presentation)

Status: Production-ready
Version: Based on Umami latest + First8 Marketing enhancements

db/postgresql/rollback/003_rollback_apache_age.sql

@@ -0,0 +1,38 @@
+-- Rollback Migration: Remove Apache AGE Graph Database
+-- Created: 2025-01-15
+-- Description: Drops Apache AGE graph and extension
+-- WARNING: This will permanently delete all graph data!
+
+-- Set search path to include ag_catalog
+SET search_path = ag_catalog, "$user", public;
+
+-- ============================================================================
+-- Step 1: Drop Helper Functions
+-- ============================================================================
+DROP FUNCTION IF EXISTS execute_cypher(text, text) CASCADE;
+
+-- ============================================================================
+-- Step 2: Drop Graph (this will cascade to all vertices and edges)
+-- ============================================================================
+SELECT ag_catalog.drop_graph('user_journey', true);
+
+-- ============================================================================
+-- Step 3: Drop Apache AGE Extension
+-- ============================================================================
+-- Note: Only drop extension if no other graphs exist
+-- Uncomment the following line if you want to completely remove Apache AGE
+-- DROP EXTENSION IF EXISTS age CASCADE;
+
+-- ============================================================================
+-- Rollback Complete
+-- ============================================================================
+DO $$
+BEGIN
+  RAISE NOTICE '=================================================================';
+  RAISE NOTICE 'Apache AGE Rollback Complete';
+  RAISE NOTICE 'Dropped graph: user_journey';
+  RAISE NOTICE 'Dropped helper functions: execute_cypher()';
+  RAISE NOTICE 'Note: Apache AGE extension was NOT dropped (may be used by other graphs)';
+  RAISE NOTICE '=================================================================';
+END $$;
+