refactor(exif): reduce cyclomatic complexity and improve performance

[rpuneet]

Summary

Refactored the EXIF parser to reduce cyclomatic complexity and improve performance through better code organization and targeted optimizations.

Changes

Code Quality Improvements

• Reduced cyclomatic complexity from 23 to 12 (48% reduction) in parseTIFF()
• Extracted parseByteOrder() helper function for byte order detection
• Extracted parseSubIFD() helper function to eliminate code duplication for EXIF and GPS sub-IFDs
• Better separation of concerns and more testable code structure

Performance Optimizations

• Pre-allocated map capacity based on entry count to reduce reallocations
• Replaced fmt.Sprintf() with string concatenation for simple cases
• Maintained proper memory safety with explicit copy for tag raw data

Benchmark Results

Before:

• 1026 ns/op
• 1632 B/op
• 31 allocs/op

After:

• 829.5 ns/op (19.2% faster ⚡)
• 1552 B/op (4.9% less memory)
• 26 allocs/op (16% fewer allocations)

Testing

• ✅ All existing tests pass
• ✅ No behavioral changes
• ✅ Fuzz tests pass
• ✅ Performance verified with benchmarks

🤖 Generated with Claude Code

[codecov]

Codecov Report

❌ Patch coverage is 84.61538% with 4 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
internal/meta/exif/exif.go	84.61%	2 Missing and 2 partials ⚠️

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