test(tools): add unit tests for error handling functions

* Implement tests for error functions like errRequiredField, errInvalidField, and errEntityNotFound.
* Ensure proper metadata is returned for various error scenarios.
* Validate error handling in CRM, Files, and other tools.
* Introduce tests for parsing stored file IDs and UUIDs.
* Enhance coverage for helper functions related to project resolution and session management.

internal/config/loader_test.go

@@ -4,6 +4,7 @@ import (
 	"os"
 	"path/filepath"
 	"testing"
+	"time"
 )
 
 func TestResolvePathPrecedence(t *testing.T) {
@@ -37,6 +38,7 @@ server:
   port: 8080
 mcp:
   path: "/mcp"
+  session_timeout: "30m"
 auth:
   keys:
     - id: "test"
@@ -80,6 +82,9 @@ logging:
 	if cfg.Server.Port != 9090 {
 		t.Fatalf("server port = %d, want 9090", cfg.Server.Port)
 	}
+	if cfg.MCP.SessionTimeout != 30*time.Minute {
+		t.Fatalf("mcp session timeout = %v, want 30m", cfg.MCP.SessionTimeout)
+	}
 }
 
 func TestLoadAppliesOllamaEnvOverrides(t *testing.T) {