chore: Update sensitive information in documentation and code to use environment variables

This commit replaces hardcoded sensitive information, such as database passwords and secret keys, in the README and deployment documentation with placeholders and instructions to use environment variables. This change enhances security by preventing exposure of sensitive data in the codebase. Additionally, it updates the database session management to raise an error if the DATABASE_URL environment variable is not set, ensuring proper configuration for development environments.

docs/DEPLOYMENT.md

@@ -34,13 +34,13 @@ This guide covers deployment of PunimTag to development and production environme
 **Development Server:**
 - **Host**: 10.0.10.121
 - **User**: appuser
-- **Password**: C0caC0la
+- **Password**: [Contact administrator for password]
 
 **Development Database:**
 - **Host**: 10.0.10.181
 - **Port**: 5432
 - **User**: ladmin
-- **Password**: C0caC0la
+- **Password**: [Contact administrator for password]
 
 ---
 
@@ -125,8 +125,8 @@ Set the following variables:
 
 ```bash
 # Development Database
-DATABASE_URL=postgresql+psycopg2://ladmin:C0caC0la@10.0.10.181:5432/punimtag
-DATABASE_URL_AUTH=postgresql+psycopg2://ladmin:C0caC0la@10.0.10.181:5432/punimtag_auth
+DATABASE_URL=postgresql+psycopg2://ladmin:[PASSWORD]@10.0.10.181:5432/punimtag
+DATABASE_URL_AUTH=postgresql+psycopg2://ladmin:[PASSWORD]@10.0.10.181:5432/punimtag_auth
 
 # JWT Secrets (change in production!)
 SECRET_KEY=dev-secret-key-change-in-production
@@ -157,8 +157,8 @@ VITE_API_URL=http://10.0.10.121:8000
 Create `viewer-frontend/.env`:
 
 ```bash
-DATABASE_URL=postgresql://ladmin:C0caC0la@10.0.10.181:5432/punimtag
-DATABASE_URL_AUTH=postgresql://ladmin:C0caC0la@10.0.10.181:5432/punimtag_auth
+DATABASE_URL=postgresql://ladmin:[PASSWORD]@10.0.10.181:5432/punimtag
+DATABASE_URL_AUTH=postgresql://ladmin:[PASSWORD]@10.0.10.181:5432/punimtag_auth
 NEXTAUTH_URL=http://10.0.10.121:3001
 NEXTAUTH_SECRET=dev-secret-key-change-in-production
 ```