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- Return lowercase error messages
- Add helper functions to handle closing HTTP response bodies and files instead
  of just deferring and not handling errors.

Add timezone configuration and validation to ensure the configured timezone is
valid on startup and during task creation. This includes adding a new `Timezone`
field to the `Config` struct and implementing a `loadLocation` function to
validate the timezone.

This change also updates the `handleCreateTask` function to use the configured
timezone when parsing natural language dates. Additionally, the default
configuration file creation has been updated to include the `Timezone` field
with a default value of "UTC".

BREAKING CHANGE: The `Timezone` field must be set in the configuration file. If
not set, the application will fail to start.

Improve error handling in handleCreateTask function by logging the API response
body when an error occurs. Update the success message to include the task ID.
Modify the createDefaultConfigFile function to use os.OpenFile instead of
os.Create for better file handling.

add goals to areas and update task creation logic to include goal validation

- remove unused list_areas and list_goals tools
- update create_task tool to validate goal_id against area
- update get_date_for_task tool to get_task_timestamp
- add list_areas_and_goals tool to list areas and goals

Add new tools to the MCP server for listing areas and their IDs, and listing
goals and their IDs. Update the LunataskCreateTaskRequest struct to include
validation rules and default values for the AreaID field.

- Adds a new tool "list_areas" to the MCP server.
- Adds a new tool "list_goals" to the MCP server.
- Updates the LunataskCreateTaskRequest struct to include validation rules and
  default values for the AreaID field.

- added support for goals in task creation
- introduced server configuration in config
- improved validation and error handling
- added default config generation on startup if config is missing
- updated task creation tool to include more parameters
- refactored task creation logic for better structure and readability