Refactor run method to simplify usage and improve flexibility

[josemachava]

Run method in the application struct to simplify its usage by removing the need for explicitly passing an address. The method now defaults to :8000 but still allows overriding it if needed.

Changes Introduced

• The Run method no longer requires an argument; it now uses a variadic parameter (address ...string).
• If no address is provided, the server defaults to :8000.
• If an address is provided, it ensures proper formatting (e.g., adding ":" if only a port is given).
• The method no longer returns an error; instead, it logs a fatal error if the server fails to start.

Why This Change?

• Simplifies the API by allowing app.Run() with a default port.
• Reduces redundant code where users previously had to pass ":8000" manually.
• Retains flexibility for specifying a custom address when needed.

Usage Example
Now, users can start the server with a default address:

app.Run() // Runs on :8000

Or specify a custom port/address:

app.Run(":8080")        // Runs on :8080  
app.Run("0.0.0.0:9090") // Runs on 0.0.0.0:9090  

Impact
This change makes the API cleaner and more user-friendly while maintaining flexibility for custom configurations.