Add web terminal, git credentials, OpenSCAD, review loops, automations

- Web terminal (PTY over WebSocket, xterm.js, sandboxed, reattach with replay)
- Per-user git credentials and commit identity (credential store in the user's home)
- OpenSCAD tool (STL/3MF + preview renders, bounding box) and cad skill; 3D model card
- Craft phase inferred from tool activity when the agent does not report it
- Configurable review loop per mode (rounds, reviewer model, criteria)
- Delete config and Markdown agents from the agent editor
- Automations: cron-scheduled agents from Markdown job files, schedule tool, page
- change_directory tool (only on the user's request)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

config.example.toml

@@ -186,6 +186,7 @@ kill_shell = "allow"
 web_fetch = "ask"
 web_search = "allow"
 diagnostics = "allow"
+openscad = "allow"     # renders .scad files to STL/3MF + previews
 browser_snapshot = "allow"
 image_compare = "allow"
 generate_image = "ask"   # costs money per image