Implements the `export` and `import` app-level commands per
ADR-0015 §11 + ADR-0007 amendment 1.
- `export [<path>]` writes a zip of project.yaml + data/ to
<data-root>/YYYYMMDD-<projectname>-export-NN.zip by default,
preserving the project's directory name as the single
top-level folder inside the archive.
- `import <zip> [as <target>]` extracts an exported zip into
a new named project and switches to it. Target name is
derived from the zip's top-level folder by default; on
collision the destination auto-suffixes -02, -03, ... up
to -99 instead of refusing (deviates from §2's refuse-on-
collision rule for save/save as; recorded as an amendment
to ADR-0015 §11).
- Excludes playground.db and history.log from the zip.
- Path-traversal protection via zip::enclosed_name + post-
resolution check that the extraction path stays inside
the target directory.
Adds the zip = "5" dep with default-features = false +
features = ["deflate"] to keep the binary-size cost modest.
Test baseline: 370 passing, 0 failing, 0 skipped.
claude@clouddev1
c6cf3df6dc