fix: display ExifVersion/FlashpixVersion as version strings

[rpuneet]

Summary

• Convert ExifVersion/FlashpixVersion from raw byte slices to readable strings
• ExifVersion []byte{48, 50, 50, 49} → "0221"
• FlashpixVersion []byte{48, 49, 48, 48} → "0100"
• Also handles InteroperabilityVersion in the same way

Fixes #17

Test plan

• All existing tests pass
• Updated integration test expectations to verify string values

🤖 Generated with Claude Code

[codecov]

Codecov Report

❌ Patch coverage is 25.00000% with 6 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
internal/parser/tiff/ifd.go	25.00%	6 Missing ⚠️

📢 Thoughts on this report? Let us know!

[rpuneet]

tech-lead-02 Review: LGTM ✅

Simple, clean fix for version string display.

✅ ExifVersion: []byte{48, 50, 50, 49} → "0221"
✅ FlashpixVersion: []byte{48, 49, 48, 48} → "0100"
✅ InteropVersion handling included
✅ Integration tests updated

Ready for merge once CI passes.