fix: rebuild review — dead include, service detection, version compare

- Removed unused <format> include from rebuild.cpp
- Service change detection simplified: any enabled service flags change
  (services aren't stored as DB entries, so element-wise compare impossible)
- Version comparison: checks if version/features/config are non-empty
  in PackageRef (conservative — rebuilds if any constraint is specified)
- Empty config with unchanged packages correctly reports 'nothing to rebuild'

src/rebuild/rebuild.cpp

@@ -1,7 +1,6 @@
 #include "kappa/rebuild/rebuild.hpp"
 #include "kappa/install/install.hpp"
 
-#include <format>
 #include <set>
 
 namespace kappa::rebuild {
@@ -27,14 +26,11 @@ ChangeSet compute_changes(const dsl::SystemConfig& cfg) {
             if (e.name != p.name) { continue; }
             found = true;
 
-            bool ver_changed = !p.version.empty()
+            bool changed = !p.version.empty()
-                            && e.version != p.version;
+                        || !p.features.empty()
-            bool feat_changed = !p.features.empty();
+                        || !p.config.empty();
-            bool cfg_changed = !p.config.empty();
 
-            if (ver_changed || feat_changed || cfg_changed) {
+            if (changed) { cs.changed.push_back(p.name); }
-                cs.changed.push_back(p.name);
-            }
             break;
         }
         if (!found) { cs.added.push_back(p.name); }
@@ -59,23 +55,7 @@ ChangeSet compute_changes(const dsl::SystemConfig& cfg) {
     }
 
     for (auto& svc : cfg.services) {
-        if (!svc.enable) { continue; }
+        if (svc.enable) { cs.services_changed = true; break; }
-        bool found = false;
-        for (auto& e : installed) {
-            if (e.name == ("svc:" + svc.name)) {
-                found = true;
-                for (auto& [k, v] : svc.config) {
-                    auto it = std::find(e.provides.begin(), e.provides.end(),
-                                       k + "=" + v);
-                    if (it == e.provides.end()) {
-                        cs.services_changed = true;
-                        break;
-                    }
-                }
-                break;
-            }
-        }
-        if (!found) { cs.services_changed = true; break; }
     }
 
     return cs;