ci: add step for installing ffmpeg

chore: linter fixes

fix: skip non-conforming piper models

docs: add `git clone` step to building from source

Fix: Handle legacy 'library' field in model metadata

Support both 'library_name' (correct) and 'library' (legacy) fields
in model card metadata to ensure compatibility with models that
use the incorrect field name in their README.md files.

This fixes issues where models with 'library: onnx' instead of
'library_name: onnx' would download successfully but fail to
appear in listings or be usable via API.

docs: update

feat: add `EOFTextChunker`

deps: update flake

docs: add Realtime API page (WIP)

docs: update openapi