Closes #260 Moves the step-0b absolute-path guard from prose instructions to a harness-enforced PreToolUse hook (gsd-worktree-path-guard.js). Hard-blocks Edit/Write/MultiEdit calls whose absolute path resolves outside the active worktree root.
Closes #260 Moves the step-0b absolute-path guard from prose instructions to a harness-enforced PreToolUse hook (gsd-worktree-path-guard.js). Hard-blocks Edit/Write/MultiEdit calls whose absolute path resolves outside the active worktree root.