Fix TOOLS.md Primary Repository Location to match runtime reality

Per LEARNINGS 2026-05-29 04:10 UTC Action Item #5. TOOLS.md says Location: /home/agent/agents/carson-engineer/mono but the repo is checked out at root /home/agent/agents/carson-engineer/. This has tripped pre-flight in May 23, 28, and 29 reflections. DoD: (a) verify current repo layout (git rev-parse --show-toplevel from root and from any nested dirs); (b) decide: either update TOOLS.md to say /home/agent/agents/carson-engineer or move the workspace to a mono/ subdirectory (likely cheaper to update the doc); (c) update TOOLS.md Primary Repository section; (d) PATCH this task to completed with result.summary.