feat(resolver): real constraint intersection and replace-aware same-name conflicts

`Pool::what_provides` previously accepted any provide/replace candidate
because `constraints_intersect` returned true unconditionally; the
same-name conflict pass also looked only at canonical names, so a
package replacing another at v1.0.0 was treated as a valid provider for
a v2.0.0 require and could coexist with the replaced package. Implement
interval-based `VersionConstraint::intersects` and index packages by
their `replace` targets (matching Composer's `getNames(false)`) when
generating same-name conflict rules.

Greens 3 installer fixtures: conflict_against_replaced_by_dep_package_problem,
provider_conflicts3, replaced_packages_should_not_be_installed.

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

1 files changed, 15 insertions, 6 deletions

diff --git a/crates/mozart-sat-resolver/src/rule_set_generator.rs b/crates/mozart-sat-resolver/src/rule_set_generator.rs
index bc56dff..83570d5 100644
--- a/crates/mozart-sat-resolver/src/rule_set_generator.rs
+++ b/crates/mozart-sat-resolver/src/rule_set_generator.rs
@@ -125,14 +125,23 @@ impl<'a> RuleSetGenerator<'a> {
             self.added_map.insert(current_id);
 
             let pkg = self.pool.package_by_id(current_id);
-            let pkg_name = pkg.name.clone();
+            let conflict_names: Vec<String> =
+                pkg.conflict_names().into_iter().map(String::from).collect();
             let requires = pkg.requires.clone();
 
-            // Index by name (for same-name conflict rules later)
-            self.added_packages_by_name
-                .entry(pkg_name)
-                .or_default()
-                .push(current_id);
+            // Index by every name this package fully claims (own name +
+            // `replace` targets). Same-name conflict rules (below) then
+            // prevent two packages from coexisting under the same logical
+            // identity. Mirrors `BasePackage::getNames(false)` indexing in
+            // Composer's RuleSetGenerator::addRulesForPackage — `provide`
+            // targets are intentionally omitted so that providers can
+            // coexist with the package they provide.
+            for name in conflict_names {
+                self.added_packages_by_name
+                    .entry(name)
+                    .or_default()
+                    .push(current_id);
+            }
 
             // Process each requirement
             for link in requires {