refactor: move package source to src/ layout (#32)

Moves sample_plugin/ into src/ to adopt the standard src-layout, which
prevents accidental imports from the source tree during tests and fixes
editable-install compatibility with mypy and other tools that rely on
proper package discovery.

- backend/sample_plugin/ moved to backend/src/sample_plugin/
- backend/pyproject.toml: add `where = ["src"]` to [tool.setuptools.packages.find]
- backend/MANIFEST.in: update recursive-include path, remove stale requirements/ lines
- backend/tox.ini: update quality tool invocations to use src/sample_plugin path

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Co-authored-by: Kyle D McCormick <kyle@axim.org>

Author: 3 people

backend/MANIFEST.in

@@ -522,8 +522,8 @@ def on_init(app):  # pylint: disable=unused-argument
         # If we are, assemble the path manually
         bin_path = os.path.abspath(os.path.join(sys.prefix, 'bin'))
         apidoc_path = os.path.join(bin_path, apidoc_path)
-    check_call([apidoc_path, '-o', docs_path, os.path.join(root_path, 'sample_plugin'),
-                os.path.join(root_path, 'sample_plugin/migrations')])
+    check_call([apidoc_path, '-o', docs_path, os.path.join(root_path, 'src/sample_plugin'),
+                os.path.join(root_path, 'src/sample_plugin/migrations')])
 
 
 def setup(app):

backend/docs/conf.py

@@ -6,7 +6,8 @@ build-backend = "setuptools.build_meta"
 name = "openedx-sample-plugin"
 description = "A sample backend plugin for the Open edX Platform"
 requires-python = ">=3.12"
-license="Apache-2.0"
+license = "Apache-2.0"
+license-files = ["LICENSE*"]
 authors = [
     {name = "Open edX Project", email = "oscm@openedx.org"},
 ]
@@ -91,12 +92,14 @@ dev = [
     "edx-i18n-tools",
 ]
 
+[tool.setuptools]
+include-package-data = true
+
 [tool.setuptools.dynamic]
 readme = {file = ["README.md"], content-type = "text/markdown" }
 
 [tool.setuptools.packages.find]
-include = ["sample_plugin*"]
-exclude = ["sample_plugin.tests*"]
+where = ["src"]
 
 [tool.semantic_release]
 # We use SETUPTOOLS_SCM_PRETEND_VERSION to pull the version from python-semantic-release instead