CLI: add JSON output to history prune dry runs

[Timi16]

Overview

History pruning currently reports human text only, which makes retention checks harder to automate.

Background

Run history is already present in the repository, but the current implementation leaves a concrete gap for users or maintainers. Relevant files: src/cli/args.rs, src/cli/commands.rs, src/history/mod.rs.

Specifications

• Add --format pretty|json to history-prune.
• Return removed and remaining counts in JSON.
• Include dry_run boolean in structured output.
• Keep current text output as the default.

Acceptance Criteria

• Behavior is covered by focused tests or documented manual verification.
• Errors are handled gracefully with actionable suggestions.
• Help text or docs are updated when the user-facing behavior changes.

[Risktaker001]

@Risktaker001 has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

Hi, I’d like to work on issue #1240. I can add JSON output support to the history prune CLI, including pretty/json formatting, structured dry-run results (removed/remaining counts), and ensure backward-compatible default behavior with tests and docs updates.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Risktaker001 to this issue.

[cyber-excel10]

@cyber-excel10 has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

Hi, i would love to add this JSON output option to the history prune command. Could you please assign this to me?

ℹ️ Repo Maintainers: To accept this application, review their application or assign @cyber-excel10 to this issue.

[mich-sys]

@mich-sys has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

hi team,
kindly assign this to me

ℹ️ Repo Maintainers: To accept this application, review their application or assign @mich-sys to this issue.

[eln4199]

@eln4199 has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

i would love to work on this

ℹ️ Repo Maintainers: To accept this application, review their application or assign @eln4199 to this issue.