chore: refuse invented capture input and geometry

[abrichr]

What changed

• Reject stored input events that lack replay-critical coordinates, button state, or key identity.
• Reject missing or invalid display metrics instead of substituting plausible geometry.
• Preserve canonical keyboard identity through event processing.

Why

A missing value must not become a valid-looking input or screen measurement. This change makes corrupt or incomplete capture data fail closed before replay or visualization.

Validation

• 145 focused tests passed locally.
• Ruff passed for every changed source and test file.
• The source-boundary guard passed.
• The branch is one exact commit on current main: d6e15c9.

No package release is part of this pull request.