feat(openclaw): support OpenClaw 2.0

[Yangtze-Seventh]

Summary

• migrate the plugin contract to OpenClaw 2026.8.1 (2.0), including exact SDK typechecking, compatibility metadata, typed media hooks, and explicit capability/conversation consent
• switch the EverOS client to the canonical /api/v2/memory/* endpoints and forward supported staged images, audio, and documents; preserve video-derived text while safely excluding unsupported raw video
• add multimodal setup and upgrade documentation, dependency-locked CI, expanded regression coverage, and an install-time version floor

Validation

• npm run ci: 144 tests, 141 passed, 3 live EverOS tests skipped, 0 failed
• exact SDK typecheck against openclaw@2026.8.1
• npm audit --omit=dev --audit-level=high: 0 vulnerabilities
• npm pack --dry-run: 25 expected files
• isolated install with the official OpenClaw 2026.8.1 CLI using --accept-capabilities
• runtime inspection: plugin loaded, 5 typed hooks registered, no compatibility diagnostics
• openclaw plugins doctor --json: ok: true, no errors or warnings
• targeted secret scan and git diff --check: clean

Notes

The three skipped tests require a running local EverOS service. The unit/contract suite covers the v2 REST paths, staged media mapping, safe multimodal fallback, consent gates, setup flow, and the exact OpenClaw 2.0 SDK surface.