fix(cli): reject non-numeric ids in cdk acknowledge

[lemon0333]

Fixes #248

cdk acknowledge <id> ran its argument through Number(), so a scoped construct warning id such as @aws-cdk/aws-ecs:minHealthyPercent became NaN and was serialized as null into acknowledged-issue-numbers in cdk.context.json — corrupting the file, while the warning still displayed.

cdk acknowledge is for numeric notice IDs; scoped construct warnings are acknowledged in code via Annotations.of(scope).acknowledgeWarning('<id>'). This validates the id is a numeric notice id and fails fast with a clear, actionable error instead of silently writing null:

Invalid notice ID '@aws-cdk/aws-ecs:minHealthyPercent': 'cdk acknowledge' only accepts numeric notice IDs (e.g. 'cdk acknowledge 12345'). Scoped construct warnings such as '@aws-cdk/aws-ecs:minHealthyPercent' are acknowledged in code with Annotations.of(scope).acknowledgeWarning('<id>').

Numeric IDs are unchanged. Added unit tests (a scoped id throws and leaves the context uncorrupted; a non-numeric id throws) — acknowledge.test.ts passes (3/3).

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:

---

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

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.33%. Comparing base (536ad69) to head (ef5bd4f).
⚠️ Report is 6 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1844   +/-   ##
=======================================
  Coverage   90.32%   90.33%           
=======================================
  Files          80       80           
  Lines       12124    12134   +10     
  Branches     1716     1718    +2     
=======================================
+ Hits        10951    10961   +10     
  Misses       1139     1139           
  Partials       34       34           

Flag	Coverage Δ
suite.unit	90.33% <100.00%> (+<0.01%)	⬆️

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