refactor: migrate to src/ package + add DinD-based E2E runner with debug artifacts

- Replace legacy standalone scripts with a proper src-layout Python package
  (baudolo backup/restore/configure entrypoints via pyproject.toml)
- Remove old scripts/files (backup-docker-to-local.py, recover-docker-from-local.sh,
  databases.csv.tpl, Todo.md)
- Add Dockerfile to build the project image for local/E2E usage
- Update Makefile: build image and run E2E via external runner script
- Add scripts/test-e2e.sh:
  - start DinD + dedicated network
  - recreate DinD data volume (and shared /tmp volume)
  - pre-pull helper images (alpine-rsync, alpine)
  - load local baudolo:local image into DinD
  - run unittest E2E suite inside DinD and abort on first failure
  - on failure: dump host+DinD diagnostics and archive shared /tmp into artifacts/
- Add artifacts/ debug outputs produced by failing E2E runs (logs, events, tmp archive)

https://chatgpt.com/share/694ec23f-0794-800f-9a59-8365bc80f435

pyproject.toml

@@ -0,0 +1,29 @@
+[build-system]
+requires = ["setuptools>=69", "wheel"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "backup-docker-to-local"
+version = "0.1.0"
+description = "Backup Docker volumes to local with rsync and optional DB dumps."
+readme = "README.md"
+requires-python = ">=3.9"
+license = { text = "AGPL-3.0-or-later" }
+authors = [{ name = "Kevin Veen-Birkenbach" }]
+
+dependencies = [
+  "pandas",
+  "dirval",
+]
+
+[project.scripts]
+baudolo = "baudolo.backup.__main__:main"
+baudolo-restore = "baudolo.restore.__main__:main"
+baudolo-configure = "baudolo.configure.__main__:main"
+
+[tool.setuptools]
+package-dir = { "" = "src" }
+
+[tool.setuptools.packages.find]
+where = ["src"]
+exclude = ["tests*"]