chore: add test-manual justfile target for jupyter-console

[blink1073]

References

Description

Adds a test-manual justfile target to make it easy to manually test the octave kernel interactively in jupyter-console.

Changes

• Added jupyter-console to the dev dependency group in pyproject.toml
• Added test-manual recipe to justfile that installs the kernel and launches jupyter-console --kernel=octave
• Updated poetry.lock

Backwards-incompatible changes

None

Testing

N/A

AI usage

• Some or all of the content of this PR was generated by AI.
• The human author has carefully reviewed this PR and run this code.
• AI tools and models used: Claude Code (claude-sonnet-4-6)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.90%. Comparing base (6f875bd) to head (721435b).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #328   +/-   ##
=======================================
  Coverage   92.90%   92.90%           
=======================================
  Files           6        6           
  Lines         437      437           
=======================================
  Hits          406      406           
  Misses         31       31           

Flag	Coverage Δ
linux	92.67% <ø> (ø)
windows	92.90% <ø> (ø)

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