feat: migrate realtime-collab from Docker Compose to k3s

Add k3s manifests for postgres, redis, and backend

Fix users table constraint and init.sql

k3s/secret.example.yaml

@@ -0,0 +1,25 @@
+apiVersion: v1
+kind: Secret
+metadata:
+  name: realtime-collab-secret
+type: Opaque
+stringData:
+  # Postgres
+  POSTGRES_USER: "replace"
+  POSTGRES_PASSWORD: "replace"
+  POSTGRES_DB: "replace"
+  # Backend
+  DATABASE_URL: "postgres://user:pass@postgres:5432/dbname?sslmode=disable"
+  REDIS_URL: "redis://redis:6379"
+  JWT_SECRET: "replace"
+  PORT: "8080"
+  ENVIRONMENT: "production"
+  BACKEND_URL: "https://collab.m1ngdaxie.com"
+  FRONTEND_URL: "https://collab.m1ngdaxie.com"
+  ALLOWED_ORIGINS: "https://collab.m1ngdaxie.com"
+  GOOGLE_CLIENT_ID: "replace"
+  GOOGLE_CLIENT_SECRET: "replace"
+  GOOGLE_REDIRECT_URL: "https://collab.m1ngdaxie.com/api/auth/google/callback"
+  GITHUB_CLIENT_ID: "replace"
+  GITHUB_CLIENT_SECRET: "replace"
+  GITHUB_REDIRECT_URL: "https://collab.m1ngdaxie.com/api/auth/github/callback"