style: Use consistent Postgres terminology in configuration

Changed 'PostgreSQL' to 'Postgres' in .env.example to align with
project terminology standards (prefer 'Postgres' over 'PostgreSQL').

Also updated section headers to use sentence-style capitalization.

Related to MR !56

Co-Authored-By: Claude <[email protected]>

Author: NikolayS

.env.example

@@ -1,9 +1,9 @@
-# PostgreSQL AI Environment Configuration
+# postgres_ai monitoring environment configuration
 # Copy this file to .env and configure with your actual values
 # NEVER commit .env to version control
 
 # =============================================================================
-# PostgreSQL Configuration (Target Database)
+# Postgres configuration (target database)
 # =============================================================================
 POSTGRES_USER=postgres
 POSTGRES_PASSWORD=changeme_secure_password
@@ -49,7 +49,7 @@ TARGET_MONITOR_USER=monitor
 TARGET_MONITOR_PASSWORD=changeme_monitor_password
 
 # =============================================================================
-# PostgreSQL Sink Database Configuration
+# Postgres sink database configuration
 # Used for storing query texts and metadata
 # =============================================================================
 SINK_POSTGRES_USER=postgres