Add pocketsphinx_to_textgrid utility for Praat TextGrid conversion

[lenzo-ka]

Description

Add pocketsphinx_to_textgrid utility to convert PocketSphinx JSON alignment output to Praat TextGrid format.

Closes #455

Features

• Converts alignment JSON from pocketsphinx align to TextGrid format
• Supports all alignment levels: words, phones, and states (depending on -phone_align / -state_align options used)
• Outputs to stdout by default, or to a file with -o
• Optional Praat integration: -w audio.wav --praat opens the result in Praat

Usage

# Basic conversion to stdout
pocketsphinx align audio.wav "hello world" | pocketsphinx_to_textgrid

# Write to file
pocketsphinx -phone_align yes align audio.wav "hello" | pocketsphinx_to_textgrid -o output.TextGrid

# Open in Praat with audio
pocketsphinx -state_align yes align audio.wav "hello" | pocketsphinx_to_textgrid -o out.TextGrid -w audio.wav --praat

Verification steps

1. Build and install the package
2. Run alignment and pipe to the utility:

   pocketsphinx -phone_align yes align test/data/goforward.raw "go forward ten meters" | pocketsphinx_to_textgrid

3. Verify TextGrid output has words and phones tiers
4. Optionally open in Praat to verify alignment visually