docs: add SQLite database setup for heartbeats processor

Add documentation and automation for SQLite database setup required
by the heartbeats processor when running 'make check' or 'make lint'.

Changes:
- Added SQLite database setup section to developer documentation
- Updated format-and-lint.sh script to automatically create the database
- Referenced tools/heartbeats-processor/schema.sql for schema creation
- Set DATABASE_URL environment variable as required by SQLx

This prevents 'database connection failed' errors when developers
run make check/lint commands.

Author: dannywillems

website/docs/developers/getting-started.mdx

@@ -155,12 +155,24 @@ make clean          # Clean build artifacts
 
 ### Environment Configuration
 
-Some components require environment variables:
+Some components require environment variables and database setup:
+
+#### SQLite Database (Required for `make check`)
+
+The heartbeats processor requires an SQLite database to be initialized before
+running `make check`:
 
 ```bash
-# For SQLx database operations (heartbeats processor)
+# Create the SQLite database with required schema
+sqlite3 /tmp/heartbeats.db < tools/heartbeats-processor/schema.sql
+
+# Set the database URL environment variable
 export DATABASE_URL="sqlite:///tmp/heartbeats.db"
+```
+
+#### Additional Environment Variables
 
+```bash
 # For archive node development
 export OPENMINA_ARCHIVE_ADDRESS="http://localhost:3007"
 export PG_USER="openmina"

website/docs/developers/scripts/setup/format-and-lint.sh

@@ -1,3 +1,8 @@
+# Set up SQLite database for heartbeats processor (required for make check/lint)
+echo "Setting up SQLite database for heartbeats processor..."
+sqlite3 /tmp/heartbeats.db < tools/heartbeats-processor/schema.sql
+export DATABASE_URL="sqlite:///tmp/heartbeats.db"
+
 # Format code (required before commits)
 echo "Formatting code..."
 make format