Show model download progress on first start

[paberr]

This branch adds first-run model download UX improvements, a warmup command, and then refines the TUI to avoid regressions and simplify the runtime step flow.

What Changed

• Added download-aware TUI progress parsing for WhisperX / HF-style output and routed it into the existing checklist/progress UI.
• Added per-step detail text support (set_detail) to the pipeline TUI so active rows can show filename/bytes/status under the bar.
• Added ownscribe warmup CLI command to prefetch transcription/diarization models without processing audio.
• Added WhisperXTranscriber.prepare_models(...) and shared model-loading/download-capture logic.
• Added a non-abstract optional prepare_models() hook to the transcriber base class.

Tests Added / Updated

• Added new progress parser + rendering tests.
• Extended transcriber tests for warmup lifecycle, download hook bar updates, per-file reset, and runtime-step routing.
• Added warmup CLI help/invocation tests.
• Added/extended pipeline warmup tests (including include_prepare=True).

[Copilot]

Pull request overview

This PR adds first-run UX improvements for model downloads by implementing download progress tracking and a warmup CLI command. The changes introduce a "Preparing models" TUI step that shows real-time download progress for WhisperX/HuggingFace models, along with a new warmup command to prefetch models before recording sessions.

Changes:

• Added download progress parsing for tqdm/HuggingFace-style output with per-step detail text support in the TUI
• Implemented ownscribe warmup CLI command to prefetch transcription/diarization models without processing audio
• Refactored transcriber model loading into shared methods with optional prepare_models() hook in the base class

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
tests/test_transcription.py	Tests for prepare_models lifecycle, download progress hooks, and runtime step routing
tests/test_progress.py	Comprehensive tests for download progress parsing, formatting, and TUI detail rendering
tests/test_pipeline.py	Tests for run_warmup command and PipelineProgress configuration
tests/test_cli.py	Tests for warmup CLI command invocation and parameter handling
src/ownscribe/transcription/whisperx_transcriber.py	Core implementation of model preparation, download capture, and progress tracking
src/ownscribe/transcription/base.py	Added optional prepare_models() hook to base Transcriber class
src/ownscribe/progress.py	Download progress parsing, formatting, and TUI detail line support
src/ownscribe/pipeline.py	run_warmup implementation with progress configuration
src/ownscribe/cli.py	warmup CLI command with model/language/diarization options
README.md	Documentation for warmup command and first-run model download behavior

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