feat: add user confirmation for keys rm command

[mootz12]

What

Add a confirmation prompt when deleting keys. The confirmation prompt can be bypassed with a --force flag. Confirmation also works by piping y into stdin.

$ stellar keys rm rmtest           
⚠️  Are you sure you want to remove the key 'rmtest' at '/my-config-path/.config/stellar/identity/rmtest.toml'? This action cannot be undone. (y/N)
y
ℹ️  Removing the key's cli config file

$ stellar keys rm rmtest --force          
ℹ️  Removing the key's cli config file

$ stellar keys rm rmtest      
⚠️  Are you sure you want to remove the key 'rmtest'? This action cannot be undone. (y/N)
N
❌ error: removal cancelled by user

Why

Closes: #2420

Known limitations

None

[fnando]

This is a breaking change, so I think we should hold it until the next protocol release.

[Copilot]

Pull request overview

Adds a safety confirmation step to stellar keys rm to prevent accidental identity deletion, with a --force escape hatch for non-interactive use. This aligns CLI behavior with the request in #2420 for destructive-action confirmation.

Changes:

• Add interactive confirmation handling to keys rm, plus a new --force flag to skip confirmation.
• Add integration tests covering confirmation-required behavior and --force.
• Update user-facing docs/help to mention --force and reflect the new behavior.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
cookbook/stellar-keys.mdx	Updates the “Remove the Identity” example command.
cmd/soroban-cli/src/commands/keys/rm.rs	Implements confirmation prompt + --force flag for key removal.
cmd/crates/soroban-test/tests/it/integration/keys.rs	Adds integration tests for confirmation and --force.
FULL_HELP_DOCS.md	Documents the new --force option in generated help.

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[leighmcculloch]

One ask otherwise lgtm.