fix: scanner + validator use qualified name for namespace-aware packages

When mcpp.toml uses `namespace = "mcpplibs"` + `name = "cmdline"`,
the scanner was passing the bare short name "cmdline" as packageName
to each SourceUnit. The validator then rejected the lib root because
`export module mcpplibs.cmdline;` != "cmdline".

Fix: scanner builds `qualifiedName = namespace + "." + name` (or bare
name if no namespace) and passes that to scan_file. The lib-root
check in validate.cppm does the same qualified comparison.

Author: Sunrisepeak

src/modgraph/scanner.cppm

@@ -341,8 +341,16 @@ void scan_one_into(ScanResult& result,
     }
     for (auto& p : excluded) all_files.erase(p);
 
+    // 0.0.6+: use qualified name (namespace.name) so the validator's
+    // "module must be prefixed by package name" check works when the
+    // manifest uses an explicit namespace field with a short name.
+    const std::string qualifiedName =
+        manifest.package.namespace_.empty()
+            ? manifest.package.name
+            : manifest.package.namespace_ + "." + manifest.package.name;
+
     for (auto const& f : all_files) {
-        auto r = scan_file(f, manifest.package.name);
+        auto r = scan_file(f, qualifiedName);
         if (!r) {
             result.errors.push_back(r.error());
             continue;

src/modgraph/validate.cppm

@@ -189,11 +189,18 @@ ValidateReport validate(const Graph&                    g,
                         "lib root '{}' exports a partition '{}' — must be the "
                         "primary module '{}' (no `:partition` suffix)",
                         lib_root_rel.string(), m, manifest.package.name)});
-                } else if (m != manifest.package.name) {
-                    r.errors.push_back({lib_unit->path, std::format(
-                        "lib root '{}' exports module '{}', expected '{}' "
-                        "(must match [package].name)",
-                        lib_root_rel.string(), m, manifest.package.name)});
+                } else {
+                    // 0.0.6+: compare against qualified name when namespace is set.
+                    const std::string expected =
+                        manifest.package.namespace_.empty()
+                            ? manifest.package.name
+                            : manifest.package.namespace_ + "." + manifest.package.name;
+                    if (m != expected) {
+                        r.errors.push_back({lib_unit->path, std::format(
+                            "lib root '{}' exports module '{}', expected '{}' "
+                            "(must match [package].namespace + name)",
+                            lib_root_rel.string(), m, expected)});
+                    }
                 }
             }
         }