feat(cli): suggest the nearest command on engine-intercepted unknowns

[qcai-godaddy]

Summary

cli-engine intercepts unknown group commands before clap parses, to emit structured unknown command "X" for "Y" errors. That early return bypasses clap's suggestion machinery — stock cli-engine gives no hint (e.g. gddy domian → unknown command "domian" for "gddy").

This change adds nearest-match hints on that path for top-level and nested typos, same plain message for humans and agents. In an interactive TTY, an optional Did you mean domain? (Y/n) prompt re-dispatches on accept. Agents, pipes, and non-TTY runs never prompt — they get the hint in the error and exit non-zero.

Mistyped commands now point at the closest real command instead of just failing:

$ gddy domian
unknown command "domian" for "gddy" — did you mean "domain"?

$ gddy domain lst
unknown command "lst" for "gddy domain" — did you mean "list"?

Testing

cli-engine local:

• cargo fmt --check
• cargo clippy --all-targets -- -D warnings (zero warnings)
• cargo test (foundation 290 + unit/integration suites)
• cargo doc -D warnings
• New unit + integration tests for edit distance, nearest match, alias/hidden
  handling, -- operands, and interactive decline paths

Integration against gddy:

• domaon / domian → suggest domain; dm → no hint
• two typos: domian lst → did you mean "gddy domain list"?
• leaf typo + operand domain avaliable example.com → "gddy domain available example.com"
• domain lst → suggest list; domain xyzzy → no hint
• domain -- lst → clap error, no hint (operand after --)
• Interactive (pty): y auto-runs gddy domain (exit 0); n → error (exit 1)

[Copilot]

Pull request overview

This PR improves cli-engine’s early “unknown command” interception path by adding nearest-match suggestions (and an optional interactive correction prompt) so typos in top-level and nested command tokens produce actionable hints instead of bypassing clap’s suggestion machinery entirely.

Changes:

• Add nearest-subcommand suggestion logic (edit distance + visibility/alias handling) to the group-router unknown-command path.
• Add an interactive Did you mean ...? confirmation prompt that can rewrite args and re-dispatch in interactive sessions.
• Extend foundation/unit tests to cover suggested hints, non-hints, and -- operand handling.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
cli-engine/tests/foundation.rs	Adds integration-style tests asserting suggested hints (and no hints) for unknown commands, including -- operand behavior.
cli-engine/src/prompt.rs	Introduces the command-correction prompt API and tests for non-interactive behavior.
cli-engine/src/cli.rs	Replaces the prior unknown-group-command message path with structured detection + nearest-match suggestion and optional interactive correction/arg rewrite.

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[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated no new comments.

[Copilot]

Pull request overview

Copilot reviewed 4 out of 5 changed files in this pull request and generated 1 comment.

[Copilot]

Pull request overview

Copilot reviewed 4 out of 5 changed files in this pull request and generated no new comments.