mpeg 1.0.0

Spawn ffmpeg and ffprobe from dart:io, probe media metadata, and inspect supported formats.

1.0.0

• Add MpegClient for running ffmpeg and ffprobe through dart:io
• Add MpegClient.isSupported() and configurable executable, environment, shell, and working-directory support
• Add direct Process.run and Process.start wrappers for both ffmpeg and ffprobe
• Add parsed ffprobe JSON helpers including format, stream, duration, bitrate, and primary video/audio lookups
• Add parsed ffmpeg / ffprobe format discovery via MpegFormat
• Add supported video extension detection for general, input, and output container support
• Add parsed version metadata via MpegVersionInfo
• Add low-risk convenience operations for transcode, remux, and still-frame extraction
• Add example usage, Docker Linux install instructions, macOS Homebrew install instructions, and ffmpeg-backed tests