feat: update Docker configuration and environment handling

- Added PostgreSQL service to docker-compose.yml with health checks and persistent storage.
- Updated bot service to use environment variable substitution for database connection string.
- Upgraded Go version in Dockerfile to 1.26.1-alpine.
- Modified config loading to ignore missing .env file for better compatibility with Docker.

Dockerfile

@@ -1,5 +1,5 @@
 # Build stage
-FROM golang:1.22-alpine AS builder
+FROM golang:1.26.1-alpine AS builder
 
 WORKDIR /app