fix: replace fmt.Errorf with signoz/pkg/errors and update golangci-li… (#9373)

This PR fulfills the requirements of #9069 by:

- Adding a golangci-lint directive (forbidigo) to disallow all fmt.Errorf usages.
- Replacing existing fmt.Errorf instances with structured errors from github.com/SigNoz/signoz/pkg/errors for consistent error classification and lint compliance.
- Verified lint and build integrity.

ee/licensing/config.go

@@ -1,10 +1,10 @@
 package licensing
 
 import (
-	"fmt"
 	"sync"
 	"time"
 
+	"github.com/SigNoz/signoz/pkg/errors"
 	"github.com/SigNoz/signoz/pkg/licensing"
 )
 
@@ -18,7 +18,7 @@ func Config(pollInterval time.Duration, failureThreshold int) licensing.Config {
 	once.Do(func() {
 		config = licensing.Config{PollInterval: pollInterval, FailureThreshold: failureThreshold}
 		if err := config.Validate(); err != nil {
-			panic(fmt.Errorf("invalid licensing config: %w", err))
+			panic(errors.WrapInternalf(err, errors.CodeInternal, "invalid licensing config"))
 		}
 	})
 

ee/zeus/config.go

@@ -1,10 +1,10 @@
 package zeus
 
 import (
-	"fmt"
 	neturl "net/url"
 	"sync"
 
+	"github.com/SigNoz/signoz/pkg/errors"
 	"github.com/SigNoz/signoz/pkg/zeus"
 )
 
@@ -24,17 +24,17 @@ func Config() zeus.Config {
 	once.Do(func() {
 		parsedURL, err := neturl.Parse(url)
 		if err != nil {
-			panic(fmt.Errorf("invalid zeus URL: %w", err))
+			panic(errors.WrapInternalf(err, errors.CodeInternal, "invalid zeus URL"))
 		}
 
 		deprecatedParsedURL, err := neturl.Parse(deprecatedURL)
 		if err != nil {
-			panic(fmt.Errorf("invalid zeus deprecated URL: %w", err))
+			panic(errors.WrapInternalf(err, errors.CodeInternal, "invalid zeus deprecated URL"))
 		}
 
 		config = zeus.Config{URL: parsedURL, DeprecatedURL: deprecatedParsedURL}
 		if err := config.Validate(); err != nil {
-			panic(fmt.Errorf("invalid zeus config: %w", err))
+			panic(errors.WrapInternalf(err, errors.CodeInternal, "invalid zeus config"))
 		}
 	})