* fix: combined tool manager improvements - tracing and redundant fetches
This PR combines improvements from #6530 and #6535:
- Add tracer import to enable proper tracing spans
- Improve update check logic to verify actual field changes before updating
- Return current_tool directly when no update is needed (avoids redundant fetch)
- Add structured tracing spans to update_tool_by_id_async for better observability
- Fix decorator order for better error handling (raise_on_invalid_id before trace_method)
- Remove unnecessary tracing spans in create_or_update_tool_async
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* revert: remove tracing spans from update_tool_by_id_async
Remove the tracer span additions from update_tool_by_id_async while keeping
all other improvements (decorator order fix, redundant fetch removal, and
improved update check logic).
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