feat(registry): support type: path repositories

Adds a `mozart-php-serialize` crate (a byte-compatible port of PHP's
`serialize()`) and a `mozart-registry::path_repository` module that
expands `type: path` entries into synthetic `type: package`
repositories. Each synthesized package carries the same SHA-1 dist
reference Composer computes (`sha1(\$json . serialize(\$options))`)
so the lockfile and trace lines match Composer byte-for-byte.

Two latent bugs surfaced once the path-repo flow exercised real
resolutions:

- `apply_partial_update` swapped path-repo packages back to their
  locked version, defeating Composer's "path repos always reload"
  rule (`PoolBuilder` treats them as canonical, not lock-bound).
  Mirror the path-repo skip already used when constructing
  `locked_packages`.
- `normalize_root_alias_atom` returned the raw input string for
  stable numeric atoms (e.g. `1.1.1`), so the alias matcher's
  `input.version \!= alias.version_normalized` check — comparing
  against pool inputs that carry the 4-segment normalized form —
  silently never matched. Run the parsed Version through Display so
  both sides are in the same shape.

`install/update::run` gain a `path_repo_base_override: Option<&Path>`
parameter for the in-process test harness: Composer's PHPUnit
`InstallerTest::setUp` does `chdir(__DIR__)` so relative path-repo
URLs resolve against `composer/tests/Composer/Test/`, but the Rust
harness writes `composer.json` into a per-test tempdir and can't
chdir safely under parallel tests. Production callers pass `None`
and resolve against `working_dir`.

Greens 3 ignored installer fixtures:
  partial_update_loads_root_aliases_for_path_repos
  alias_in_lock
  alias_in_lock2

1 files changed, 5 insertions, 0 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 48e0f4d..697c3d0 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1179,6 +1179,10 @@ dependencies = [
 ]
 
 [[package]]
+name = "mozart-php-serialize"
+version = "0.1.0"
+
+[[package]]
 name = "mozart-registry"
 version = "0.1.0"
 dependencies = [
@@ -1190,6 +1194,7 @@ dependencies = [
  "md5",
  "mozart-core",
  "mozart-metadata-minifier",
+ "mozart-php-serialize",
  "mozart-sat-resolver",
  "mozart-semver",
  "mozart-vcs",