feat: terminal startup command and container tools

- Add startup_command field to ToolType model and API
- Execute startup command before interactive shell in terminal sessions
- Add tmux and ranger to OpenCode container spec
- Update Tool Workshop UI with startup_command input for terminal types
- Add backend tests for startup_command CRUD operations
- Sync specs: tool-terminal, tool-types-definition, opencode-web-server
- New spec: tool-terminal-startup-command

Quality gates: Frontend typecheck/lint passed. Backend tests blocked by environment (Python/Docker not available).

OpenSpec: terminal-startup-and-container-tools

openspec/specs/opencode-web-server/spec.md

@@ -9,6 +9,8 @@ The system SHALL configure OpenCode containers to run a web server accessible on
 - **WHEN** the container starts
 - **THEN** a web server is running on port 3000 inside the container
 - **AND** the server serves a web terminal interface
+- **AND** the container has `tmux` installed
+- **AND** the container has `ranger` installed
 
 ### Requirement: OpenCode exposes web interface
 
@@ -37,3 +39,4 @@ The system SHALL serve a functional web terminal interface for OpenCode.
 - **WHEN** the user clicks the "Open" button
 - **THEN** a new tab opens with the OpenCode web interface
 - **AND** the interface shows a terminal connected to the OpenCode process
+- **AND** the user can run `tmux` and `ranger` commands