fix(gateway): block silent shared-service takeover

[artemgetmann]

Review Fast Path

• User path fixed: plain openclaw gateway install can no longer silently overwrite the sacred default shared gateway service when another runtime/worktree already owns it.
• Proof: pnpm test -- src/cli/daemon-cli/install.test.ts src/cli/daemon-cli/install.integration.test.ts src/cli/daemon-cli/register-service-commands.test.ts and pnpm build both passed in this worktree.
• Shared-state footgun removed: the default shared service now fails closed on ownership drift and only allows replacement with --force --allow-shared-service-takeover; profiled tester/consumer/rescue lanes remain allowed.
• Still hurts: this does not auto-fix already-misconfigured lanes, and I did not run a live launchd takeover E2E against the real machine label because that would be reckless.

Why This Matters

• Consumer/tester worktrees were able to hijack ai.openclaw.gateway, which took the main Telegram bot down.
• The repo already documented isolated profiles, but docs alone were not enough. The CLI needed a hard stop.

Scope Boundary

• Added install-time ownership detection for the default shared gateway service.
• Added an explicit --allow-shared-service-takeover escape hatch for intentional recovery.
• Added regression tests and short workflow reminders in AGENTS.md and docs/gateway/multiple-gateways.md.
• Did not change multi-bot/profile support, token routing, or runtime restart behavior.

Verification

• pnpm test -- src/cli/daemon-cli/install.test.ts src/cli/daemon-cli/install.integration.test.ts src/cli/daemon-cli/register-service-commands.test.ts
• pnpm build
• Test coverage includes:
  • blocking takeover when the installed shared service points at another runtime/config
  • allowing explicit takeover with --allow-shared-service-takeover
  • skipping the guard for profiled installs so isolated tester lanes still work

AI Assistance

• AI-assisted
• Testing degree: targeted