Fix lost key/mouse events and scroll accumulation within a frame (#847)

[Element119rd]

Description

Fixes the input handling bug reported in #847, where clicks, key presses, and mouse wheel notches get lost within a single frame.

Changes

-- Replaced single state event maps in InputManager with separate per-frame flag maps (m_keyPressed, m_keyReleased, m_mouseButtonPressed, m_mouseButtonReleased).
-- Changed OnMouseScroll to accumulate deltas (+=) instead of overwriting.
-- Updated ClearEvents() to reset scroll vector and clear frame flags.
-- Kept public API signature unchanged.

Related Issue(s)

Fixes #847

Review Guidance

Main changes are in InputManager.cpp / .h.
ClearEvents() logic remains tied to the end-of-frame tick,

How to test

1. Build the project.
2. Add the repro script from the issue to any actor, press Play.
3. Tap quickly on a touchpad a few times , each tap should log both Left button down and Left button up.
4. Spin the mouse wheel fast , logged scroll values should reflect the sum of notches received during the frame,
5. verify normal held keys/buttons still behave correctly.

Screenshots/GIFs

none!

AI Usage Disclosure

none!

Checklist

• My code follows the project's code style guidelines
• When applicable, I have commented my code, particularly in hard-to-understand areas
• When applicable, I have updated the documentation accordingly
• My changes don't generate new warnings or errors
• I have reviewed and take responsibility for all code in this PR (including any AI-assisted contributions)