praisonai-platform: list_issue_activity returns activity log for any issue regardless of workspace ownership

PraisonAI Platform is the platform layer for the PraisonAI multi-agent teams system. Versions prior to 0.1.4 have an Insecure Direct Object Reference. The `GET /workspaces/{workspace_id}/issues/{issue_id}/activity` endpoint is gated by `require_workspace_member(workspace_id)` and dispatches to `ActivityService.list_for_issue(issue_id)`, which executes `SELECT * FROM activity WHERE issue_id = :issue_id` with no workspace constraint. A user who is a member of any workspace can read the full activity log of any issue across the entire multi-tenant deployment. PraisonAI Platform version 0.1.4 patches the issue.