Remove stale saved setup schema

[jasonsuhari]

Problem

GridBash no longer exposes the old saved setup composer flow, but the config and setup modules still carry stale saved-setup schema and helper APIs.

Requested behavior

Remove the dead saved-setup config/schema surface while keeping the current startup picker, direct launch path, and managed worktree launch behavior intact.

Acceptance checks

• Saved setup types and config storage are removed from current main.
• Existing configs with legacy [setups] tables do not break parsing.
• Startup picker and direct launch planning still compile with managed worktree support.
• npm test passes.