Align prune defaults to delete all non-running runs

[vm-mishchenko]

Summary

Remove the --all flag from draft prune and change its default behavior to delete every non-running run in the selected project scope, not just successfully finished ones.

Add a run status classification system (classify_run) that categorizes runs as running, done, stopped, missing, or corrupt. Use this to make the selection process and output more transparent: the selection list now shows each run's status and is grouped by status (done → stopped → missing → corrupt) with descending run-id within groups.

Update the summary line format from deleted N; skipped M active; selected K to deleted N; skipped M active, printed on all code paths including no-op and dry-run. When the current project has no non-running runs but other projects do, provide a helpful hint mentioning the count and --all-projects flag (suppressed when --project is explicit).

Update draft delete output to include the resolved project name: deleted run <id> (project: <project>). Update README documentation accordingly.

Test plan

• Added test_prune_status_grouping_order: verifies selection groups by status and sorts run-ids descending within each group
• Added test_prune_all_projects_hint_fires: confirms hint appears when current project is empty and other projects have non-running runs
• Added test_prune_all_projects_hint_suppressed_under_project_flag: confirms hint does not appear when --project is explicit
• Added test_prune_status_column_in_selection_line: verifies status column appears in selection output
• Added test_prune_all_flag_rejected: confirms parser rejects --all with non-zero exit
• Renamed and updated test_prune_all_includes_incomplete → test_prune_default_includes_incomplete: verifies default now includes non-finished runs
• Renamed and updated test_prune_all_skips_active → test_prune_default_skips_active: verifies default still skips active runs
• Updated test_prune_no_runs: assertion changed to new summary format
• Updated test_prune_yes_deletes_run: assertion changed to new summary format
• Updated test_command_delete_with_delete_branch_flag and test_command_delete_without_flag_skips_branch_deletion: assertions verify project name in output
• Updated test_prune_one_finished_one_in_progress_default_selection: verifies both finished and partial runs appear in selection with correct statuses
• Existing tests continue to pass with removal of include_all parameter