refactor: move package source to src/ layout

[feanil]

Summary

• Moves backend/sample_plugin/ to backend/src/sample_plugin/ to adopt the standard src/ layout
• Adds where = ["src"] to [tool.setuptools.packages.find] in backend/pyproject.toml
• Updates backend/MANIFEST.in to use the new path and removes stale requirements/ lines
• Updates backend/tox.ini quality commands (pylint, pycodestyle, pydocstyle, isort) to reference src/sample_plugin

Motivated by feedback on openedx/public-engineering#506: the src/ layout prevents accidental imports from the source tree during tests and fixes editable-install compatibility with mypy and other static analysis tools.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.40%. Comparing base (0884981) to head (e87b157).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #32      +/-   ##
==========================================
+ Coverage   88.23%   88.40%   +0.17%     
==========================================
  Files          13       14       +1     
  Lines         408      414       +6     
  Branches       16       16              
==========================================
+ Hits          360      366       +6     
  Misses         40       40              
  Partials        8        8              

Flag	Coverage Δ
unittests	88.40% <ø> (+0.17%)	⬆️

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[bradenmacdonald]

Thanks @feanil ! I tested this by making an editable install into my edx-platform venv, and it seems to be working well. I left some suggestions but feel free to save them for a future PR.

[bradenmacdonald]

Nit: I think if you put the following in, you can delete MANIFEST.in:

Suggested change

	[tool.setuptools.package-data]
	# Include these data files when building the wheel, if any are present in src/
	sample_plugin = ["**/*.html", "**/*.png", "**/*.gif", "**/*.js", "**/*.css", "**/*.jpg", "**/*.jpeg", "**/*.svg"]

Or, since we're using setuptools-scm, we could use:

[tool.setuptools]
include-package-data = true

to pull in all files in src tracked by git without needing to maintain this separate list of file extensions.

[bradenmacdonald]

Also, whether using MANIFEST.in or package-data in pyproject.toml, I would recommend creating an empty py.typed file at src/sample_plugin/py.typed and then adding "py.typed", to this list, e.g. sample_plugin = ["py.typed", "**/*.html", "**/*.png", ... so that mypy will pick up any type definitions if other python projects are importing and using this code. Not so necessary for a plugin but very important for any reusable libraries.

[bradenmacdonald]

Suggested change

exclude = ["sample_plugin.tests*"]

I think this exclude is not necessary when you have where = ["src"] and the tests are outside of the src folder.

[kdmccormick]

I'll remove include = ["sample_plugin*"] too, since the existence of a src folder makes me expect that anything within src should be included.

[bradenmacdonald]

Nit: replace with ruff ?

[kdmccormick]

Will follow up #33

[farhan]

Please add following in project.toml and remove it and readme declaration from Manifest.in
license-files = ["LICENSE.txt"]

[kdmccormick]

Nice, nothing to add beyond what Farhan and Braden have said.