This commit introduces the ability to handle log files through the API and
provides a new log viewing page. The API now supports GET and DELETE methods
for log file operations, allowing retrieval and deletion of log contents.
A new log.html page has been added for viewing logs in the browser, with
automatic refresh every 5 seconds and styling based on log levels.

The app.go file has been updated to include a GetLogFilepath function that
retrieves or generates the log file path. The NewLogger function now accepts
a file parameter to enable file logging. The main.js file has been updated
to include a link to the new log.html page.

This enhancement improves the observability and management of the application
by providing real-time access to logs and the ability to clear them directly
from the web interface.

This commit refactors the log handling in the API to use a switch statement for improved readability and maintainability. It also introduces error messages with more context when reading or truncating the log file fails.

On the frontend, a new auto-update toggle button has been added to the log viewer, allowing users to enable or disable automatic log updates. The button's appearance changes based on its state, providing a clear visual indication of whether auto-update is active. Additionally, the button styling has been updated to ensure consistency across the interface.