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/mcpserver/eventstore_test.go

@@ -0,0 +1,30 @@
+package mcpserver
+
+import (
+	"context"
+	"testing"
+
+	"github.com/google/uuid"
+	"github.com/modelcontextprotocol/go-sdk/mcp"
+
+	"git.warky.dev/wdevs/amcs/internal/session"
+)
+
+func TestCleanupEventStoreSessionClosedClearsActiveProject(t *testing.T) {
+	activeProjects := session.NewActiveProjects()
+	activeProjects.Set("session-1", uuid.New())
+
+	store := newCleanupEventStore(mcp.NewMemoryEventStore(nil), activeProjects.Clear)
+
+	if _, ok := activeProjects.Get("session-1"); !ok {
+		t.Fatal("active project missing before SessionClosed")
+	}
+
+	if err := store.SessionClosed(context.Background(), "session-1"); err != nil {
+		t.Fatalf("SessionClosed() error = %v", err)
+	}
+
+	if _, ok := activeProjects.Get("session-1"); ok {
+		t.Fatal("active project still present after SessionClosed")
+	}
+}