Warn and fail closed for sync ToolNode enforcement

[Muhammad-usman92]

Summary

• Warn during adrian.init() when WebSocket enforcement is enabled without a running event loop.
• Fail closed in sync ToolNode.invoke when policy state is not ready yet, or when BLOCK/HITL mode is active but no resolved verdict is available.
• Reuse existing blocked ToolMessage behaviour: [BLOCKED by security policy].
• Keep async ToolNode.ainvoke behaviour unchanged.

Test plan

• Added SDK regression coverage for sync ToolNode.invoke fail-closed enforcement.
• Added SDK coverage for the init warning when no running event loop exists.
• Ran focused SDK tests: 21 passed.
• Ran ruff on changed SDK files.

Checklist

• CLA signed (see CLA.md)
• Tests pass locally
• Docs updated where needed
• British English; no em-dashes; no marketing fluff

[yanny-sec]

Sorry to keep you waiting on this PR and thank you for your contribution! Could you rebase onto current main and solve the conflicts?

[Muhammad-usman92]

Sorry to keep you waiting on this PR and thank you for your contribution! Could you rebase onto current main and solve the conflicts?

Absolutely! I'll rebase the PR onto the latest main branch and resolve the merge conflicts.