docs: Enable Ruff formatting of Python code blocks in Markdown (#78)

### What & why

Ruff 0.16 formats Python code blocks embedded in Markdown files, and
does so by default. In this repo the feature was inert twice over: the
Ruff pin was `~=0.14.0`, which has no Markdown support at all, and
`[tool.ruff] include` was an allowlist of `*.py` globs, so no Markdown
file would have reached the formatter anyway.

This bumps Ruff to `~=0.16.0` and adds `**/*.md` and `**/*.mdx` to
`include`, together with the `extension = { mdx = "markdown" }` mapping
that MDX needs (without it Ruff would try to parse `.mdx` as Python and
fail). There is no Markdown in this repo containing Python code blocks
today, so no file content changes - this is here to keep the four Apify
Python repos configured identically.

Ruff 0.16 flags `CPY001` (missing copyright notice) under `select =
["ALL"]`, so it is added to the ignore list, matching apify-sdk-python,
apify-client-python and crawlee-python.

No changes to the `lint` / `format` Poe tasks are needed. `lint` already
runs `ruff format --check` and `format` already runs `ruff format`, so
both pick Markdown up automatically. Note that `ruff check` (lint rules)
does not support Markdown yet, so only formatting is enforced there.

### Notes

- The second commit collapses the `include` allowlist to a single
`**/*.py` glob. This is a pure simplification: no tracked `.py` file
lives outside `src/` and `tests/`, and Ruff processes exactly the same 8
files before and after.

*✍️ Drafted by Claude Code*

Author: vdusek

pyproject.toml

@@ -50,7 +50,7 @@ dev = [
     "pytest-timeout<3.0.0",
     "pytest-xdist<4.0.0",
     "pytest<10.0.0",
-    "ruff~=0.14.0",
+    "ruff~=0.16.0",
     "setuptools", # setuptools are used by pytest, but not explicitly required
     "ty~=0.0.0",
 ]
@@ -61,12 +61,20 @@ source-include = ["CHANGELOG.md", "CONTRIBUTING.md"]
 
 [tool.ruff]
 line-length = 120
-include = ["src/**/*.py", "tests/**/*.py"]
+include = [
+    "**/*.py",
+    # Ruff formats Python code blocks embedded in Markdown files.
+    "**/*.md",
+    "**/*.mdx",
+]
+# MDX is Markdown; without this mapping Ruff would try to parse `.mdx` files as Python.
+extension = { mdx = "markdown" }
 
 [tool.ruff.lint]
 select = ["ALL"]
 ignore = [
     "COM812", # This rule may cause conflicts when used with the formatter
+    "CPY001", # Missing copyright notice at top of file
     "D100",   # Missing docstring in public module
     "D104",   # Missing docstring in public package
     "D107",   # Missing docstring in `__init__`