feat(makernote/canon): implement Canon MakerNote parser

[rpuneet]

Summary

• Implements Canon MakerNote parser (MNI-2, Issue MNI-2: Canon MakerNote Parser #11)
• Handler with detection, IFD parsing, 70+ tag name mappings
• Handles all TIFF data types including inline data
• Canon format: no header, IFD at offset 0, absolute offsets

Test plan

• Unit tests for Manufacturer(), Detect(), Parse(), TagName()
• Tests for inline data handling
• Tests for both little-endian and big-endian
• All 22 packages passing

🤖 Generated with Claude Code

[codecov]

Codecov Report

❌ Patch coverage is 37.37374% with 186 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
internal/parser/tiff/makernote/canon/canon.go	37.37%	167 Missing and 19 partials ⚠️

📢 Thoughts on this report? Let us know!

[rpuneet]

Review: Canon MakerNote Parser (tech-lead-01)

Status: APPROVED ✅

Summary

Comprehensive Canon MakerNote implementation matching our design spec.

Positive Findings

1. Format handling correct:

   • No header, IFD at offset 0 ✓
   • Absolute offsets (relative to EXIF TIFF header) ✓
   • Inherits byte order, tries LE first then BE ✓
   • Ignores next-IFD pointer (CR2 quirk) ✓

2. Implementation (585 lines):

   • All TIFF data types supported (BYTE through SRATIONAL)
   • Inline data optimization (<=4 bytes in value field)
   • 70+ tag name mappings

3. Tests (305 lines):

   • Detect validation (entry count, type checks)
   • Parse with constructed test data
   • Inline data handling
   • Both LE and BE byte order

4. Detection robustness:

   • Validates entry count 1-100
   • Checks first entry has valid tag type (1-12)
   • Won't false-positive on Nikon headers

LGTM. Merging now.