Merge main into dev: bring dev up to date with restructured package

Resolves add/add conflicts in .gitignore, config.yaml, pyproject.toml and
content conflict in README.md — taking main's version in all cases, as it
reflects the complete package rewrite (gallery/ package, TUI, CI pipeline).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitignore

@@ -1 +1,10 @@
-__pycache__
+**__pycache__**
+.vscode
+*.sif
+*.ipynb
+backups
+.pytest_cache
+.venv
+build
+*egg-info
+.claude