fix: properly annotate EventCallback.fn for tests

[benedikt-bartscher]

[greptile-apps]

Greptile Summary

The PR adds a static-only annotation for EventCallback.fn, matching the raw state method exposed through the runtime EventHandler, and removes now-unnecessary Pyright suppressions from event tests.

• Declares the fn callable attribute under TYPE_CHECKING.
• Verifies background-task marker access without attribute-access suppressions.

Confidence Score: 5/5

The PR appears safe to merge.

No blocking failure remains.

Important Files Changed

Filename	Overview
packages/reflex-base/src/reflex_base/event/init.py	Adds a type-checking-only fn annotation whose leading state parameter matches the raw undecorated method stored by EventHandler.
tests/units/test_event.py	Removes obsolete Pyright suppressions from existing runtime assertions without changing test behavior.

_{Reviews (2): Last reviewed commit: "rewrite comment with one ai to make anot..." | Re-trigger Greptile}

[codspeed-hq]

Merging this PR will not alter performance

✅ 26 untouched benchmarks
⏩ 8 skipped benchmarks¹

---

_{Comparing benedikt-bartscher:improve-event-handler-typing-in-tests (fbcc20e) with main (092aa4f)}

Footnotes

1. 8 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[cubic-dev-ai]

All reported issues were addressed across 2 files

<sub>Reply with feedback, questions, or to request a fix.

Re-trigger cubic</sub>