[codex] Split public Dhee into Developer Brain

[Ashish-dwi99]

Summary

• Repositions public Dhee as Dhee Developer Brain for local memory, handoff, repo/folder linking, and git-backed shared context.
• Removes public UI surfaces from this repository: dhee/ui and the older apps/cognitive-debugger frontend app.
• Adds dhee repo/dhee link shared-context plumbing with append-only .dhee/context/entries.jsonl, conflict detection, and a pre-push guard for unresolved context edits.
• Keeps enterprise dashboard/code-intelligence/commercial work out of public Dhee; that now lives in the private Sankhya-AI/dhee-enterprise repo.

Validation

• Clean local clone of codex/developer-brain-split.
• PYTHONPATH=. /Users/chitranjanmalviya/Desktop/Dhee/.venv-dhee/bin/python -m pytest tests/test_cli_onboard_update.py tests/test_repo_link.py tests/test_harness_install.py -q -> 36 passed.
• /Users/chitranjanmalviya/Desktop/Dhee/.venv-dhee/bin/python -m py_compile dhee/cli.py dhee/cli_onboard.py dhee/cli_update.py dhee/repo_link.py dhee/hooks/claude_code/__main__.py dhee/hooks/claude_code/renderer.py.
• /Users/chitranjanmalviya/Desktop/Dhee/.venv-dhee/bin/python -m build --sdist --wheel.
• Inspected clean sdist and wheel: 0 dhee/ui, apps/cognitive-debugger, or enterprise paths.

Notes

This PR intentionally does not include unrelated local router/runtime edits still present in the working tree.