fix(audio): support full MPEG Layer III sync header detection for MP3

[AdamMagued]

Summary

Fixes #91

Root Cause Analysis

Previously, matchers.Mp3 only matched ID3 tags (0x49 0x44 0x33) and MPEG-1 Layer III audio frames without CRC protection (0xFF 0xFB). However, MP3 audio frames can use other valid MPEG versions (such as MPEG-2 Layer III used for lower sample rates like 16, 22.05, 24 kHz, or MPEG-2.5) as well as CRC-protected frames (where the protection bit is set to 0). When an MP3 without an ID3 container begins directly with an MPEG-2 Layer III frame header (e.g., 0xFF 0xF3 or 0xFF 0xF2), matchers.Mp3 returned false, causing the file to not be detected as MP3.

Changes

• Updated matchers.Mp3 to validate all MPEG Layer III frame headers using standard bitmask checks:
  • First byte must be 0xFF.
  • Second byte sync word bits (0xE0) combined with Layer III description bits (0x02) are checked via (buf[1] & 0xE6) == 0xE2.
  • Audio version bits (buf[1] & 0x18) are verified not to equal 0x08 (the reserved version ID), properly admitting MPEG-1, MPEG-2, and MPEG-2.5 Layer III frames with or without CRC.
• Added comprehensive unit tests in matchers/audio_test.go covering ID3 tags, MPEG-1, MPEG-2, and MPEG-2.5 Layer III sync headers with and without CRC, as well as invalid versions, other MPEG layers, and non-MPEG headers.
• Added test cases in match_test.go verifying end-to-end detection.

Test Verification

• All tests pass via go test -v ./... with 100% pass rate.