fix(dashboard): discover experiments in flat work-dir layout

[raunaqness]

Summary

Fixes the Streamlit dashboard not listing experiments when using the default standalone local work directory layout.

• Detect workdir/checkpoints/ directly under --work-dir (flat layout used by plexe.main)
• Normalize numbered checkpoint phase names (e.g. 06_package_final_model) when inferring phase number and completion status

Problem

python -m plexe.main --work-dir ./plexe_workdir ... writes artifacts to:

plexe_workdir/
├── checkpoints/
├── model/
└── .build/

But python -m plexe.viz --work-dir ./plexe_workdir reported "No experiments found" because discover_experiments() only scanned nested paths like workdir/{dataset_name}/checkpoints/.

Reproduced after a successful end-to-end build on the Rain in Australia dataset (weatherAUS, PyPI 1.4.4, Python 3.12).

Fix

• Add flat-layout detection when workdir/checkpoints/ exists
• Strip numeric prefix from checkpoint phase before phase/status mapping so completed runs show correctly

Test plan

• poetry run pytest tests/unit/utils/dashboard/test_discovery.py -v
• poetry run pytest tests/unit/ -q
• Manually verified discover_experiments(Path("./plexe_workdir_clean")) returns 1 experiment
• Manually verified python -m plexe.viz --work-dir ./plexe_workdir_clean lists the experiment in the sidebar

[vaibs-d]

Thanks for raising this! @raunaqness
We’ll review this now

[raunaqness]

@vaibs-d Bumped version to 1.4.5 for the version-check CI requirement. Local version check + unit tests pass. This should address the failing Verify Version Bump check.