Route annotated command help through the application output stream

[AryanRG]

For commands decorated with @with_annotated, --help currently writes to process stdout instead of the cmd2 application output stream. For example, greet --help > help.txt leaves the requested file empty. The equivalent @with_argparser path already routes parser output through the application stream.

Wrap annotated argument parsing in the existing parser output_to(app.stdout) context. This covers both normal and unknown-argument parsing, including nested subcommands. Add regressions for application capture, overwrite redirection, append redirection, and no process-stdout leakage. The changelog notes the user-visible fix.

Local validation on macOS / Python 3.13.12:

• 15 new regressions failed on the unchanged base and passed with the fix.
• make check passed, including Ruff, ty, mypy, and documentation formatting.
• make test: 2,023 passed, 3 skipped.
• make docs-test passed.

Other operating systems and Python versions remain for hosted CI. AI assistance was used to investigate, implement, review, and test this change.

Closes #1776

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.75%. Comparing base (93cfe81) to head (74cec46).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1779   +/-   ##
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  Coverage   99.75%   99.75%           
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  Files          23       23           
  Lines        6473     6474    +1     
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+ Hits         6457     6458    +1     
  Misses         16       16           

Flag	Coverage Δ
unittests	99.75% <100.00%> (+<0.01%)	⬆️

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