Add camera reset functionality (R key) and fix build

[TECHNICANGEL]

This PR implements a "Reset Camera" feature (requested as a micro-UX improvement).

Changes:

1. Fixed Compilation Error: Removed duplicate declarations of currentFPS and frameTimeMs in src/main.cpp which were preventing the project from building.
2. Camera Class Update: Added initialPosition, initialYaw, initialPitch, and initialFov members to Camera.h and initialized them in the constructor. Added a reset() method to restore these values.
3. Input Handling: Updated keyCallback in src/main.cpp to listen for the 'R' key.
4. UX Feedback: When 'R' is pressed, the camera resets, a log message is printed, and the window title (status bar) is updated immediately to reflect the new position.

This change allows users to easily recover from disorientation while navigating the 3D scene.

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PR created automatically by Jules for task 5182742576547245750 started by @TECHNICANGEL

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