fix(alerting): Support custom slack title

[mehdiMj-ir]

Summary

Support for custom Slack title via configuration #927

Fixes #927

Checklist

• Tested and/or added tests to validate that the changes work as intended, if applicable.
• Updated documentation in README.md, if applicable.

[mehdiMj-ir]

Could you please review this pull request? If it suits your application, feel free to merge it into the main codebase or alternatively, write your own version if preferred.
I currently run two instances of this app: one for internal requests and another for external ones. I'd like to customize the title.

[TwiN]

Can you revert all indentation changes?

[mehdiMj-ir]

I'm sorry I overlooked the indentation and didn't follow your workflow preference of using tabs instead of spaces.

[TwiN]

Code looks fine, but can you add a test?

[TwiN]

@mehdiMj-ir fyi it's not my workflow preference, it's what gofmt does.

Tbf I care more about consistency than specific preferences

[mehdiMj-ir]

TBH, I'm a sysAdmin, not a programmer 😅
I really love your project because it lets me document and organize our URLs on our GitLab.
It's great that you're so consistent with your work, it’s already shaping up to be an excellent product.
I'll add a test and follow up with you soon.

[mehdiMj-ir]

I am indeed sorry, I am not a programmer. I tried chatGPT but it's not like your code and it have a hard coded url

Go test code.

func TestAlertProvider_WithCustomTitle(t *testing.T) {
	provider := Provider{
		Title:      "🚨 Custom Title 🚨",
		WebhookURL: "https://hooks.slack.com/test-webhook",
	}
	alert := &alert.Alert{
		Description: "Service is DOWN",
	}
	endpoint := &core.Endpoint{
		Name: "my-service",
	}
	result := &core.Result{
		Success: false,
	}
	body, err := provider.buildRequestBody(alert, endpoint, result)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if !strings.Contains(body, provider.Title) {
		t.Errorf("expected body to contain custom title %q, got: %s", provider.Title, body)
	}
}

func TestAlertProvider_DefaultTitleWhenEmpty(t *testing.T) {
	provider := Provider{
		WebhookURL: "https://hooks.slack.com/test-webhook",
		// Title left empty
	}
	alert := &alert.Alert{
		Description: "Service is DOWN",
	}
	endpoint := &core.Endpoint{
		Name: "my-service",
	}
	result := &core.Result{
		Success: false,
	}
	body, err := provider.buildRequestBody(alert, endpoint, result)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	// Default title should fallback to endpoint name
	if !strings.Contains(body, "my-service") {
		t.Errorf("expected body to contain default title %q, got: %s", "my-service", body)
	}
}

Once again, I am sorry.

[TwiN]

@mehdiMj-ir There's no need to be sorry, don't worry.

Re-open your PR, I'll add the tests myself when I have a moment 🙂