refactor(workspace): pass workspace object instead of id to service methods

- Replace workspace_id parameter with Workspace object reference in all workspace service methods
- Remove redundant find_workspace_by_id calls that were duplicated in each method
- Update all method signatures across approval, audit, billing, branding, core, settings and stats modules
- Modify SQL queries to bind ws.id instead of separate workspace_id parameter
- Add Workspace import to all affected modules
- Adjust method calls in API handlers to pass workspace object instead of id
- Consolidate workspace retrieval logic to single location per operation flow

api/workspace/get.rs

@@ -0,0 +1,34 @@
+use actix_web::{HttpResponse, web};
+
+use crate::api::response::{ApiErrorResponse, ApiResponse};
+use crate::error::AppError;
+use crate::models::workspaces::Workspace;
+use crate::service::AppService;
+use crate::session::Session;
+
+#[utoipa::path(
+    get,
+    path = "/api/v1/workspaces/{workspace_name}",
+    tag = "Workspaces",
+    operation_id = "workspaceGet",
+    summary = "Get a workspace",
+    description = "Return the workspace identified by name, subject to visibility checks.",
+    params(
+        ("workspace_name" = String, Path, description = "Workspace name.")
+    ),
+    responses(
+        (status = 200, description = "Workspace data.", body = ApiResponse<Workspace>),
+        (status = 401, description = "Unauthenticated.", body = ApiErrorResponse),
+        (status = 404, description = "Workspace not found or not accessible.", body = ApiErrorResponse),
+        (status = 500, description = "Database read failed.", body = ApiErrorResponse)
+    )
+)]
+pub async fn handle(
+    service: web::Data<AppService>,
+    session: Session,
+    path: web::Path<String>,
+) -> Result<HttpResponse, AppError> {
+    let ws = service.workspace.find_workspace_by_name(&path).await?;
+    let data = service.workspace.workspace_get(&session, &ws).await?;
+    Ok(HttpResponse::Ok().json(ApiResponse::new(data)))
+}