fix(mcp): search returns empty results after container restart

[husniadil]

Summary

Fix FalkorDB driver factory to read FALKORDB_DATABASE from environment variable, consistent with how FALKORDB_URI and FALKORDB_PASSWORD are already handled.

Type of Change

• Bug fix
• New feature
• Performance improvement
• Documentation/Tests

Objective

The FALKORDB_DATABASE environment variable was being ignored in create_config(). The code always used the default value from config (falkor_config.database), causing the MCP server to connect to the wrong graph database when FALKORDB_DATABASE was set via environment variable.

This fix aligns the database parameter with the existing pattern used for uri and password on lines 420-421.

Testing

• Unit tests added/updated
• Integration tests added/updated
• All existing tests pass

Manual testing performed:

1. Set FALKORDB_DATABASE=main in .env
2. Started MCP server, added memory to graph
3. Restarted container
4. Verified search returns persisted data (confirms correct database connection)

Breaking Changes

• This PR contains breaking changes

If this is a breaking change, describe:

• What functionality is affected
• Migration path for existing users

Checklist

• Code follows project style guidelines (make lint passes)
• Self-review completed
• Documentation updated where necessary
• No secrets or sensitive information committed

Related Issues

Closes #[issue number]

[danielchalef]

All contributors have signed the CLA ✍️ ✅
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[husniadil]

I have read the CLA Document and I hereby sign the CLA