sea: add test and update docs for import() with code cache

[thisalihassan]

• Remove the **Note:** import() does not work when useCodeCache is true. restriction from the API documentation.

Assisted by: Claude Opus 4.6

[nodejs-github-bot]

Review requested:

• @nodejs/single-executable

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.80%. Comparing base (de5644c) to head (731eff1).
⚠️ Report is 18 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #62678      +/-   ##
==========================================
- Coverage   89.81%   89.80%   -0.02%     
==========================================
  Files         699      699              
  Lines      216235   216465     +230     
  Branches    41336    41380      +44     
==========================================
+ Hits       194216   194387     +171     
- Misses      14129    14150      +21     
- Partials     7890     7928      +38     

Files with missing lines	Coverage Δ
src/node_sea.cc	89.53% <ø> (ø)

... and 49 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.