Iteration 5: export / import commands

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.

Cargo.lock

@@ -2,6 +2,12 @@
 # It is not intended for manual editing.
 version = 4
 
+[[package]]
+name = "adler2"
+version = "2.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "320119579fcad9c21884f5c4861d16174d0e06250625266f50fe6898340abefa"
+
 [[package]]
 name = "aho-corasick"
 version = "1.1.4"
@@ -32,6 +38,15 @@ dependencies = [
  "object",
 ]
 
+[[package]]
+name = "arbitrary"
+version = "1.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c3d036a3c4ab069c7b410a2ce876bd74808d2d0888a82667669f8e783a898bf1"
+dependencies = [
+ "derive_arbitrary",
+]
+
 [[package]]
 name = "atomic"
 version = "0.6.1"
@@ -215,6 +230,15 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "crc32fast"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9481c1c90cbf2ac953f07c8d4a58aa3945c425b7185c9154d67a65e4230da511"
+dependencies = [
+ "cfg-if",
+]
+
 [[package]]
 name = "crossterm"
 version = "0.29.0"
@@ -333,6 +357,17 @@ dependencies = [
  "powerfmt",
 ]
 
+[[package]]
+name = "derive_arbitrary"
+version = "1.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1e567bd82dcff979e4b03460c307b3cdc9e96fde3d73bed1496d2bc75d9dd62a"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.117",
+]
+
 [[package]]
 name = "derive_more"
 version = "2.1.1"
@@ -495,6 +530,16 @@ version = "0.4.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0ce7134b9999ecaf8bcd65542e436736ef32ddca1b3e06094cb6ec5755203b80"
 
+[[package]]
+name = "flate2"
+version = "1.1.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "843fba2746e448b37e26a819579957415c8cef339bf08564fe8b7ddbd959573c"
+dependencies = [
+ "miniz_oxide",
+ "zlib-rs",
+]
+
 [[package]]
 name = "fnv"
 version = "1.0.7"
@@ -897,6 +942,16 @@ version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "68354c5c6bd36d73ff3feceb05efa59b6acb7626617f4962be322a825e61f79a"
 
+[[package]]
+name = "miniz_oxide"
+version = "0.8.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1fa76a2c86f704bdb222d66965fb3d63269ce38518b83cb0575fca855ebb6316"
+dependencies = [
+ "adler2",
+ "simd-adler32",
+]
+
 [[package]]
 name = "mio"
 version = "1.2.0"
@@ -1378,6 +1433,7 @@ dependencies = [
  "tokio",
  "tracing",
  "tracing-subscriber",
+ "zip",
 ]
 
 [[package]]
@@ -1615,6 +1671,12 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "simd-adler32"
+version = "0.3.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "703d5c7ef118737c72f1af64ad2f6f8c5e1921f818cdcb97b8fe6fc69bf66214"
+
 [[package]]
 name = "similar"
 version = "2.7.0"
@@ -2486,8 +2548,40 @@ version = "1.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "cfe53a6657fd280eaa890a3bc59152892ffa3e30101319d168b781ed6529b049"
 
+[[package]]
+name = "zip"
+version = "5.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2f852905151ac8d4d06fdca66520a661c09730a74c6d4e2b0f27b436b382e532"
+dependencies = [
+ "arbitrary",
+ "crc32fast",
+ "flate2",
+ "indexmap",
+ "memchr",
+ "zopfli",
+]
+
+[[package]]
+name = "zlib-rs"
+version = "0.6.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3be3d40e40a133f9c916ee3f9f4fa2d9d63435b5fbe1bfc6d9dae0aa0ada1513"
+
 [[package]]
 name = "zmij"
 version = "1.0.21"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b8848ee67ecc8aedbaf3e4122217aff892639231befc6a1b58d29fff4c2cabaa"
+
+[[package]]
+name = "zopfli"
+version = "0.8.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f05cd8797d63865425ff89b5c4a48804f35ba0ce8d125800027ad6017d2b5249"
+dependencies = [
+ "bumpalo",
+ "crc32fast",
+ "log",
+ "simd-adler32",
+]