Drop support for antigravity, openclaw, cursor, and windsurf adapters

[aommi]

Proposal

Remove 4 adapters, keeping only the 3 that are actively used: hermes, claude-code, and codex.

Adapters to remove

Adapter	Reason
antigravity	Google-internal IDE; no personal use case
openclaw	No active usage
cursor	Generated files already cause clutter (see #8); disabled in all projects
windsurf	Same as cursor — disabled everywhere, no usage

Adapters to keep

Adapter	Why
claude-code	Primary coding agent; hooks-enforced
codex	Used alongside Claude; shares AGENTS.md with hermes
hermes	Runs the gateway, reads AGENTS.md natively

Scope

• Remove adapter files: adapters/antigravity.py, adapters/openclaw.py, adapters/cursor.py, adapters/windsurf.py
• Remove from generate.py: AGENTS dict, AGENT_OUTPUTS, ALL_ORDER, cmd_init defaults
• Remove templates: templates/antigravity/
• Update README: agent table, setup docs, architecture diagram
• Update agent-memory-kit-management skill
• Clean up .gitignore entries for removed adapter output dirs (.cursor/, .cursorignore, .agents/, .openclaw-system.md, .windsurfrules, GEMINI.md — wait, gemini-cli stays? check)

Impact on consumers

• applycling: already has all 4 agents disabled. No impact — their generated files were already cleaned up (f3269fa).
• New projects from init: won't see these agents as options.
• Existing projects: generate.py all will skip removed adapters (they're not in ALL_ORDER). Manual generate.py cursor will error — intentional.