chore(config): remove dragonflydb and update deployment documentation

Remove all references to DragonflyDB from the codebase, environment templates, and documentation following its removal from the service architecture. This includes cleaning up Docker configurations, CI/CD workflows, and production guides.

- **Cleanup**: Deleted `dragonfly.conf` and removed DragonflyDB service from `docker-compose.yml`.
- **Environment**: Removed `DRAGONFLY_PASSWORD` and `DRAGONFLY_ADDR` from `.env.example` and `docker-entrypoint.sh`.
- **Documentation**: Updated `README.md`, `PRODUCTION_DEPLOYMENT.md`, and `QUICK_START_PRODUCTION.md` to reflect a 2-service architecture (Trackeep + Postgres).
- **CI/CD**: Updated GitHub Actions to use Go 1.25.
- **Testing**: Updated `test-production.sh` to remove DragonflyDB variable validation.

PRODUCTION_DEPLOYMENT.md

@@ -8,7 +8,6 @@ This guide provides comprehensive instructions for deploying Trackeep to product
 ### System Requirements
 - Docker 24.0+ and Docker Compose 2.20+
 - PostgreSQL 15+
-- DragonflyDB (Redis-compatible cache)
 - 2GB+ RAM minimum (4GB+ recommended)
 - 20GB+ disk space
 
@@ -22,11 +21,6 @@ DB_PASSWORD=<strong-password>
 DB_NAME=trackeep
 DB_SSL_MODE=disable
 
-# DragonflyDB (Cache)
-DRAGONFLY_ADDR=dragonfly:6379
-DRAGONFLY_PASSWORD=<strong-password>
-DRAGONFLY_PORT=6379
-
 # Security
 JWT_SECRET=<generate-with-openssl-rand-base64-32>
 ENCRYPTION_KEY=<generate-with-openssl-rand-base64-32>
@@ -250,19 +244,6 @@ sqlDB.SetConnMaxLifetime(time.Hour)
 sqlDB.SetConnMaxIdleTime(10 * time.Minute)
 ```
 
-### DragonflyDB Configuration
-
-```yaml
-# docker-compose.prod.yml
-dragonfly:
-  command: >
-    dragonfly
-    --requirepass=${DRAGONFLY_PASSWORD}
-    --proactor_threads=4
-    --maxmemory=2gb
-    --maxmemory-policy=allkeys-lru
-```
-
 ### Frontend Optimization
 
 ```bash