feat: chat history, inline file editor, split terminal, OCI resource actions, and layout fixes
- Add ChatGPT-style chat history for Chat Agent and Terraform Agent (sessions, rename, delete)
- Add inline .tf file editor with Tab support and auto-sync to workspace code
- Add split-panel terminal showing Plan/Apply/Destroy output alongside files/plan/resources
- Add OCI resource actions: start/stop Compute instances and Autonomous DBs from Resources panel
- Add multi-file Terraform generation via // filename: markers
- Fix GenAI empty response handling (GPT-5.2 fallback message)
- Fix compartment select visibility, Terraform code block light theme
- Fix page layout overflow (no more scroll beyond viewport)
- Add DB migration for terraform_workspaces.compartment_id column
- Update README with new features, API endpoints, and version notes
8bccf9367e