XY-711: Stalled recovery P1: make retained partial progress a first-class outcome

[yvette-carlisle]

Summary

• Add a first-class stalled retained-partial-progress disposition for dirty retained worktrees.
• Keep clean/no-progress stalled lanes on the existing stalled_run_detected attention path.
• Update runtime and Linear ledger specs plus regressions for dirty and no-progress stalled recovery.

Validation

• cargo make fmt
• cargo make lint-fix
• cargo make test