Camera calibration with ChArUco board on screen (no printer)

[joaquinpary]

Description

Add a guided camera calibration flow that allows the user to point the camera at a ChArUco board displayed on the screen (no need to print it). The system auto-captures valid views, calculates intrinsic and distortion parameters, and saves a JSON profile that is automatically applied in future sessions.

Acceptance Criteria

• A "Calibrate" button starts the guided flow (30–60 seconds).
• The ChArUco board is shown on screen (no printing required).
• The system auto-captures views and shows real-time progress.
• Upon completion, a before/after correction preview is shown.
• The calibration profile is saved as JSON and reused when relaunching RIVeR.
• In low light conditions, "too blurry" is displayed and resumes upon improvement.
• The CLI is updated to support the new flow.

Notes

Implement on the branch feature/issue-109-camera-calibration.