chore: remove medium publishing kit from repo

Move local-only. Medium-specific artifacts (rendered PNGs, cleaned
markdown, posting guide) belong on disk for one-off publication, not
in the public repo. Use Typora locally for the paste workflow.

.gitignore now excludes medium/ and medium_local/.

Author: Tanay10x

.gitignore

@@ -35,3 +35,7 @@ dist/
 .pytest_cache/
 .ruff_cache/
 .mypy_cache/
+
+# Local-only publishing artifacts
+medium/
+medium_local/