chore: rename log level environment variable to TASKMASTER_LOG_LEVEL (#417)

* chore: rename log level environment variable to `TASKMASTER_LOG_LEVEL`

### CHANGES
- Update environment variable from `LOG_LEVEL` to `TASKMASTER_LOG_LEVEL`.
- Reflect change in documentation for clarity.
- Adjust variable name in script and test files.
- Maintain default log level as `info`.

* fix: add changeset

* chore: rename `LOG_LEVEL` to `TASKMASTER_LOG_LEVEL` for consistency

### CHANGES
- Update environment variable name to `TASKMASTER_LOG_LEVEL` in documentation.
- Reflect rename in configuration rules for clarity.
- Maintain consistency across project configuration settings.

tests/setup.js

@@ -9,7 +9,7 @@ process.env.MODEL = 'sonar-pro';
 process.env.MAX_TOKENS = '64000';
 process.env.TEMPERATURE = '0.2';
 process.env.DEBUG = 'false';
-process.env.LOG_LEVEL = 'error'; // Set to error to reduce noise in tests
+process.env.TASKMASTER_LOG_LEVEL = 'error'; // Set to error to reduce noise in tests
 process.env.DEFAULT_SUBTASKS = '5';
 process.env.DEFAULT_PRIORITY = 'medium';
 process.env.PROJECT_NAME = 'Test Project';