Refactor token management, client initialization, and project handling

- Consolidated `TokenStorage` struct into `internal/auth/models.go` for better organization.
- Updated `Client` to use `TokenStorage` for managing email and project ID.
- Simplified `SetupUser` method to ensure proper token and project assignment.
- Refactored API handlers to leverage new `GetEmail` and `GetProjectID` methods in `Client`.
- Cleanup: Removed unused structures and redundant code from `client.go` and `auth.go`.
- Adjusted CLI flow in `login.go` and `run.go` for streamlined user onboarding.

internal/auth/models.go

@@ -0,0 +1,9 @@
+package auth
+
+type TokenStorage struct {
+	Token     any    `json:"token"`
+	ProjectID string `json:"project_id"`
+	Email     string `json:"email"`
+	Auto      bool   `json:"auto"`
+	Checked   bool   `json:"checked"`
+}