Add strict mode for video corruption detection

[IanButterworth]

Add a strict::Bool = false keyword to openvideo / VideoReader. When enabled, the underlying codec context is opened with AV_EF_EXPLODE | AV_EF_CRCCHECK | AV_EF_BITSTREAM, so bitstream / CRC errors propagate out of avcodec_receive_frame instead of being silently concealed. These errors surface to the caller as a VideoCorruptionError.

This makes decoding deterministic across FFmpeg versions for callers that need data integrity (no synthetic pixels from error concealment), while the default behaviour is unchanged.

• Export VideoCorruptionError
• Set err_recognition flags before avcodec_open2 when strict=true
• Wrap the existing decode-error path in decode() to throw VideoCorruptionError instead of a plain error() when strict
• Documentation in docs/src/reading.md and CHANGELOG.md
• Tests covering the new keyword, exception type, normal-mode pass-through, and corruption detection via a malformed H.264 Annex-B bitstream

[codecov]

Codecov Report

❌ Patch coverage is 80.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 79.45%. Comparing base (e9e6e2e) to head (a86e431).

Files with missing lines	Patch %	Lines
src/avio.jl	80.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #453      +/-   ##
==========================================
- Coverage   80.05%   79.45%   -0.60%     
==========================================
  Files          10       10              
  Lines        1499     1504       +5     
==========================================
- Hits         1200     1195       -5     
- Misses        299      309      +10     

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