add final soft confirmation hash to batch proof output

[eyusufatik]

Closes #1423

[codecov]

Codecov Report

Attention: Patch coverage is 7.14286% with 13 lines in your changes missing coverage. Please review.

Project coverage is 76.8%. Comparing base (4f86cea) to head (8e0427d).
Report is 1 commits behind head on nightly.

Files with missing lines	Patch %	Lines
crates/citrea-stf/src/verifier.rs	0.0%	13 Missing ⚠️

Additional details and impacted files

Files with missing lines	Coverage Δ
crates/batch-prover/src/proving.rs	89.5% <100.0%> (-1.4%)	⬇️
...n-sdk/rollup-interface/src/state_machine/zk/mod.rs	50.0% <ø> (ø)
crates/citrea-stf/src/verifier.rs	0.0% <0.0%> (ø)

... and 5 files with indirect coverage changes