Fix Opik traces missing after plugin registry reloads

[codeofthrone]

Summary

Fixes a two-part issue where Opik traces stopped being recorded after a configuration change caused a plugin registry reload in the OpenClaw gateway.

Changes

• Module-level Shared State: Moved client, tags, projectName, and toolResultPersistSanitizeEnabled from per-instance closure variables to module-level variables in src/service.ts.
• Early Hook Registration: Moved api.on hook registrations from service.start() to the body of createOpikService.
• Getter Functions for Hooks: Changed tags and projectName to getter functions in LlmHooksDeps and ToolHooksDeps.
• Hook Guards: Added a guard to the agent_end hook and the tool_result_persist hook to safely no-op until the service is started.

Testing

• Unit tests updated and passing (98 tests passed).
• Confirmed traces are correctly produced after registry reloads.

Checklist

• Tests pass
• Documentation updated
• No breaking changes

[vincentkoc]

Closing this as superseded.

The underlying regression was addressed on main and released in @opik/opik-openclaw@0.2.10, and the tracker already moved forward through the later compatibility work rather than this branch. I want to keep contributor credit clear here: this PR was absolutely in the right bug family, but it is now stale/dirty against current main and we already have the released fix plus end-to-end coverage on top.