[Core]: While creating an invoice, if a client is not already in the system allow the user via the search box to add a new client on the go #67

Context

Especially in busy environments adding a client instantly would be time efficient.

Specific:

As a user, I want to be able to add a new client with minimal required information on a single screen.

Measurable:

The time taken to add a new client will be reduced by 50% compared to the current process.

Achievable:

Very should require minimal programming.
In essence create a link in
https://invoice.hhaufe.eu/index.php/clients/form
when searching and no clients are found text is displayed: (No results found)
This would change to: (No results found | Would you like to create a new client?)
This link would call the create_invoice invoice form and when completed return to create invoice.

Relevant:

This feature directly addresses the need for improved efficiency in client management, especially during peak periods.

Time-bound:

This feature will be implemented and tested within a two-week sprint.

Extra info:

In the file modal_create_invoice.php line 33 it is said it wil create a new client so perhaps part of the code is already there to avoid double work.
$('#invoice_create_confirm').click(function () { // Posts the data to validate and create the invoice; // will create the new client if necessar

Arrange:

// Create a user with the necessary permissions to add clients
$user = User::factory()->create(['role' => 'administrator']);
$this->actingAs($user);

// Define the minimal required client data
$clientData = [
'name' => 'Test Client',
'email' => 'test@example.com',
];

Act:

// Submit a POST request to the client creation endpoint with the minimal required data
$response = $this->post(route('clients.store'), $clientData);

Assert:

// Assert that the client was successfully created in the database
$response->assertRedirect(route('clients.index'));
$this->assertDatabaseHas('clients', $clientData);

// Assert that the form validation was successful by checking for no error messages
$response->assertSessionHasNoErrors();

@spacecabbie I'm assigning this one to you so you can keep an eye on it.
Each module will have this functionality: Add invoice, Client doesn't exist, create it right there on the spot.
Same for quotes, expenses, you name it