feat: add kappa search <query> subcommand

Searches all cached indexes in $KAPPA_ROOT/cache/indexes/
for packages matching the query as a substring. Displays
name, version, and repo source (e.g. 'make 4.4.1 @ kappa-os/stable').
Offline — no network requests.

src/main.cpp

@@ -53,6 +53,7 @@ Subcommands:
   list                    List installed packages
   rollback                Show available generations
   index        <dir>      Build an index.kap from .kap files in a directory
+  search       <query>    Search cached indexes for packages
   add          <pkg> [v]  Add a package to system config (optional version)
                   --features "key=on,key2=off"   Set feature flags
                   --config   "key=val,key2=val2" Set config values
@@ -223,6 +224,7 @@ int main(int argc, char* argv[]) {
                            || (subcommand == "fetch-package")
                            || (subcommand == "rollback")
                            || (subcommand == "index")
+                           || (subcommand == "search")
                            || (subcommand == "add")
                            || (subcommand == "remove");
 
@@ -341,6 +343,50 @@ int main(int argc, char* argv[]) {
         }
     }
 
+    if (subcommand == "search") {
+        if (file_arg == nullptr) {
+            std::cerr << "error: no search query specified\n";
+            return 1;
+        }
+        auto idx_dir = paths::cache_dir() / "indexes";
+        std::error_code ec;
+        if (!std::filesystem::exists(idx_dir)) {
+            std::cout << "no cached indexes — run kappa fetch-package <name> first\n";
+            return 0;
+        }
+
+        std::string_view query(file_arg);
+        int found = 0;
+        for (auto& entry : std::filesystem::directory_iterator(idx_dir, ec)) {
+            if (ec) break;
+            auto ext = entry.path().extension().string();
+            if (ext != ".kap") continue;
+
+            std::ifstream in(entry.path());
+            if (!in) continue;
+            std::ostringstream buf;
+            buf << in.rdbuf();
+
+            try {
+                auto idx = dsl::parse_index(buf.str());
+                for (auto& pkg : idx.packages) {
+                    if (pkg.name.find(query) != std::string::npos) {
+                        std::cout << pkg.name << " " << pkg.version
+                                  << " @ " << idx.name << "\n";
+                        found++;
+                    }
+                }
+            } catch (...) { continue; }
+        }
+
+        if (found == 0) {
+            std::cout << "no packages matching '" << query << "'\n";
+        } else {
+            std::cout << found << " result(s)\n";
+        }
+        return 0;
+    }
+
     if (subcommand == "add") {
         if (file_arg == nullptr) {
             std::cerr << "error: no package name specified\n";