feat(cli): improve interactive prompt UI with @clack/prompts

[mrgrain]

Improves the interactive CLI experience for deploy approvals, text prompts, and the flags command by adopting @clack/prompts — a modern, actively maintained prompt library with beautiful default styling.

The CLI previously relied on promptly and enquirer for user interaction, both of which are unmaintained and produce plain, unstyled output. @clack/prompts provides a consistent, visually polished prompt experience out of the box, with clear confirmation dialogs, styled select menus, and proper cancellation handling via Ctrl+C.

Beyond the immediate UI improvements, this also lays the groundwork for richer CLI interactions in the future. @clack/prompts ships with spinner, taskLog, and structured logging utilities that can be used to improve deploy progress, asset upload feedback, and other long-running operations.

Before / After

Deploy approval

Before

After

Flags interactive menu

Before

After

Text input

Before

After

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Since @clack/prompts is an ESM-only package and Jest runs in CJS mode, a global mock file is provided at test/_helpers/mock-clack-prompts.js. This is appropriate because prompt functions are inherently interactive and should always be mocked in tests. The bundled CLI binary is unaffected since esbuild handles ESM→CJS interop at build time.

Fixes #

Checklist

• This change contains a major version upgrade for a dependency and I confirm all breaking changes are addressed
  • Release notes for the new version: N/A — this replaces two packages with a new one, not an upgrade

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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license

[codecov-commenter]

Codecov Report

❌ Patch coverage is 72.88136% with 16 lines in your changes missing coverage. Please review.
✅ Project coverage is 88.20%. Comparing base (7ce6a36) to head (a06c7e8).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
.../aws-cdk/lib/commands/flags/interactive-handler.ts	64.51%	11 Missing ⚠️
packages/aws-cdk/lib/cli/io-host/cli-io-host.ts	82.14%	4 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1370      +/-   ##
==========================================
- Coverage   88.31%   88.20%   -0.12%     
==========================================
  Files          74       74              
  Lines       10430    10458      +28     
  Branches     1427     1432       +5     
==========================================
+ Hits         9211     9224      +13     
- Misses       1191     1206      +15     
  Partials       28       28              

Flag	Coverage Δ
suite.unit	88.20% <72.88%> (-0.12%)	⬇️

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