Report per-run counts in stck push summary

[brdv]

Summary

Make stck push summary counts reflect work performed in the current run, not total plan size.

Changelist

• src/cli.rs
  • Captures starting progress counters before push/retarget loops.
  • Computes pushed_this_run and retargeted_this_run from completed deltas.
  • Updates final summary message to report per-run counts.
• tests/cli_skeleton.rs
  • Updated push summary expectations for both fresh and resumed runs.

Validation

• cargo fmt --all
• cargo clippy --all-targets --all-features -- -D warnings
• cargo test --all-features