fix(resolver): seed root package into pool as fixed entry

Composer's RootPackageRepository puts a clone of the root package into
the pool as a fixed entry — its `require` / `require-dev` cleared, but
its name, version, provides, and replaces preserved. That way a
transitive `require` pointing back at the root resolves through the
pool the same way any other reference would, and legal circular
dependencies (root requires A, A requires root) work.

Mozart had no such seed: the rule generator only knew about the root
through the explicit root-require / root-provide / root-replace tables,
so a transitive consumer requiring the root by name failed with no
provider.

Plumb root_version through ResolveRequest (RawPackageData gains a
matching `Option<String>` field), build a fixed PoolPackageInput for
the root with provides/replaces lifted from request.root_provide /
root_replace, and skip the root by name when collecting the resolver's
output so it doesn't leak into the lock file. Falls back to
`1.0.0+no-version-set` (Composer's RootPackage::DEFAULT_PRETTY_VERSION)
when the root composer.json omits `version`.

Unblocks circular_dependency2, conflict_against_replaced_package_problem,
and provider_conflicts installer fixtures.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/crates/mozart-core/src/package.rs b/crates/mozart-core/src/package.rs
index 02ec935..8bda13d 100644
--- a/crates/mozart-core/src/package.rs
+++ b/crates/mozart-core/src/package.rs
@@ -461,6 +461,13 @@ pub struct RawPackageData {
     #[serde(default = "default_root_package_name")]
     pub name: String,
 
+    /// Root project's version, when explicitly set. Composer falls back to
+    /// `1.0.0+no-version-set` when this is missing; we keep the raw `Option`
+    /// here and let the resolver apply that default so the in-memory shape
+    /// stays close to the JSON input.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub version: Option<String>,
+
     #[serde(skip_serializing_if = "Option::is_none")]
     pub description: Option<String>,
 
@@ -554,6 +561,7 @@ impl RawPackageData {
     pub fn new(name: String) -> Self {
         Self {
             name,
+            version: None,
             description: None,
             package_type: None,
             homepage: None,