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

artifacts/debug-dind-20251226180030.txt

@@ -0,0 +1,25 @@
+=== docker -H ps -a ===
+CONTAINER ID   IMAGE     COMMAND   CREATED   STATUS    PORTS     NAMES
+
+=== docker -H images ===
+WARNING: This output is designed for human readability. For machine-readable output, please use --format.
+IMAGE                                             ID             DISK USAGE   CONTENT SIZE   EXTRA
+alpine:3.20                                       765942a40399       12.2MB         3.71MB        
+baudolo:local                                     0bc9b158f3e8        763MB          368MB        
+ghcr.io/kevinveenbirkenbach/alpine-rsync:latest   049c6ec3dad7       21.1MB         7.53MB        
+
+=== docker -H network ls ===
+NETWORK ID     NAME      DRIVER    SCOPE
+43f0f11bd281   bridge    bridge    local
+2390bc99b893   host      host      local
+0f26ae890b2e   none      null      local
+
+=== docker -H volume ls ===
+DRIVER    VOLUME NAME
+
+=== docker -H system df ===
+TYPE            TOTAL     ACTIVE    SIZE      RECLAIMABLE
+Images          3         0         796.2MB   10.82kB (0%)
+Containers      0         0         0B        0B
+Local Volumes   0         0         0B        0B
+Build Cache     0         0         0B        0B