Support filename pattern grouping in cross-validation CLI

[gbeane]

Summary

The filename-pattern cross-validation grouping strategy (added in #398) was wired into the GUI, Project.get_labeled_features, and project settings, but the jabs-cli cross-validation command was left incomplete — there was no way to select or configure it from the CLI. This PR closes that gap.

What was missing

1. --grouping-strategy only accepted video and individual — FILENAME_PATTERN was unreachable.
2. run_cross_validation had no grouping_regex parameter, so even if the strategy could be selected, no regex could reach the layer that requires it (compile_grouping_regex raises on an empty pattern).
3. The training report read grouping strategy/regex directly from project settings, so a CLI override would not be reflected in the report.

Changes

scripts/cli/cli.py

• Added filename to the --grouping-strategy choices.
• Added a --grouping-pattern option for the regex (falls back to the project's saved pattern when omitted).
• Replaced the if/elif chain with a name→enum mapping and forwarded the pattern as grouping_regex.

scripts/cli/cross_validation.py

• Added a grouping_regex: str | None parameter, documented it, and passed it to get_labeled_features.
• Resolved the effective strategy/regex (CLI override → project settings) so the training report records what was actually used. The regex is only emitted when the effective strategy is FILENAME_PATTERN (also fixes a pre-existing minor issue where a stale saved regex could appear in the report for non-filename strategies).

tests/scripts/test_cross_validation_cli.py (new)

• 7 tests covering enum mapping (incl. case-insensitivity), regex forwarding, None defaults, and rejection of unknown strategies, using a run_cross_validation spy so they're fast and need no real project.

Example

uv run jabs-cli cross-validation /path/to/project --behavior Walk \
    --grouping-strategy filename --grouping-pattern '^(\w+?)_'

Testing

• New tests: 7 passed. Related grouping suites (test_cv_grouping in core and project): 23 passed total.
• ruff check clean; ruff format applied.
• jabs-cli cross-validation --help renders both new options correctly.

[Copilot]

Pull request overview

This PR completes wiring of the filename-pattern cross-validation grouping strategy into the jabs-cli cross-validation command, allowing the strategy and its regex to be selected/configured via CLI and ensuring the training report reflects the effective settings actually used.

Changes:

• Extended --grouping-strategy to include filename and added --grouping-pattern for the regex override.
• Threaded an optional grouping_regex through run_cross_validation() into Project.get_labeled_features().
• Updated report generation to record the effective grouping strategy/regex (CLI override → project settings), emitting the regex only for filename-pattern grouping.
• Added CLI parsing tests using a run_cross_validation spy for fast option→argument verification.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
src/jabs/scripts/cli/cli.py	Adds filename grouping option, --grouping-pattern, and maps CLI strings to the enum; forwards regex override.
src/jabs/scripts/cli/cross_validation.py	Adds grouping_regex parameter, forwards to feature extraction, and records effective grouping settings in the report.
tests/scripts/test_cross_validation_cli.py	New tests validating Click parsing/mapping and argument forwarding to run_cross_validation.

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