Rework the package layout towards my these-days "usual" one.

    * tox -> nox
    * nox-based GH Actions
    * setuptools -> hatchling
    * flake8 -> ruff
    * no src/
    * random pyright flailing (which probably still is a regression but
      I haven't gotten a chance to look into + report it)
    * probably a small additional thing or two

No functional changes still, yet.

Author: Julian

.flake8

@@ -0,0 +1,15 @@
+# Security Policy
+
+## Supported Versions
+
+In general, only the latest released `referencing` version is supported and will receive updates.
+
+## Reporting a Vulnerability
+
+To report a security vulnerability, please send an email to `Julian+Security` at `GrayVines.com` with subject line `SECURITY (referencing)`.
+
+I will do my best to respond within 48 hours to acknowledge the message and discuss further steps.
+
+If the vulnerability is accepted, an advisory will be sent out via GitHub's security advisory functionality.
+
+For non-sensitive discussion related to this policy itself, feel free to open an issue on the issue tracker.

.github/CODEOWNERS

@@ -0,0 +1,16 @@
+version: 2
+updates:
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+
+  - package-ecosystem: "pip"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+
+  - package-ecosystem: "pip"
+    directory: "/docs"
+    schedule:
+      interval: "weekly"

.github/SECURITY.md

@@ -0,0 +1,5 @@
+changelog:
+  exclude:
+    authors:
+      - dependabot
+      - pre-commit-ci

.github/dependabot.yml

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+name: CI
+
+on:
+  push:
+    tags:
+      - "v*"
+  pull_request:
+  release:
+    types: [published]
+  schedule:
+    # Daily at 8:33
+    - cron: "33 8 * * *"
+
+env:
+  PIP_DISABLE_PIP_VERSION_CHECK: "1"
+  PIP_NO_PYTHON_VERSION_WARNING: "1"
+
+jobs:
+  list:
+    runs-on: ubuntu-latest
+    outputs:
+      noxenvs: ${{ steps.noxenvs-matrix.outputs.noxenvs }}
+    steps:
+      - uses: actions/checkout@v4
+      - name: Set up nox
+        uses: wntrblm/[email protected]
+      - id: noxenvs-matrix
+        run: |
+          echo >>$GITHUB_OUTPUT noxenvs=$(
+            nox --list-sessions --json | jq '[.[].session]'
+          )
+
+  ci:
+    needs: list
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        noxenv: ${{ fromJson(needs.list.outputs.noxenvs) }}
+        posargs: [""]
+        include:
+          - noxenv: tests-3.11
+            posargs: coverage github
+
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          submodules: "recursive"
+      - name: Install dependencies
+        run: sudo apt-get update && sudo apt-get install -y libenchant-2-dev
+        if: runner.os == 'Linux' && startsWith(matrix.noxenv, 'docs')
+      - name: Install dependencies
+        run: brew install enchant
+        if: runner.os == 'macOS' && startsWith(matrix.noxenv, 'docs')
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: |
+            3.8
+            3.9
+            3.10
+            3.11
+            3.12
+            pypy3.10
+          allow-prereleases: true
+          cache: pip
+      - name: Set up nox
+        uses: wntrblm/[email protected]
+      - name: Run nox
+        run: nox -s "${{ matrix.noxenv }}" -- ${{ matrix.posargs }}
+
+  packaging:
+    needs: ci
+    runs-on: ubuntu-latest
+    environment:
+      name: PyPI
+      url: https://pypi.org/p/schemastore
+    permissions:
+      contents: write
+      id-token: write
+
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          submodules: "recursive"
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          cache: pip
+          python-version: "3.x"
+      - name: Install dependencies
+        run: python -m pip install build
+      - name: Create packages
+        run: python -m build .
+      - name: Publish to PyPI
+        if: github.event_name == 'push' && startsWith(github.event.ref, 'refs/tags')
+        uses: pypa/gh-action-pypi-publish@release/v1
+      - name: Create a Release
+        if: github.event_name == 'push' && startsWith(github.event.ref, 'refs/tags')
+        uses: softprops/action-gh-release@v2
+        with:
+          files: |
+            dist/*
+          generate_release_notes: true