feat: system-agnostic package manager — 5 inits, 2 bootloaders, parallel scheduler

Complete rewrite of kappa from a sequential build tool into a
system-agnostic package manager with runtime init switching.

Core additions:
- 5 init system backends: systemd, openrc, s6, runit, dinit
  (service file generation, enable/disable, init_paths)
- 2 bootloader backends: grub, limine (config generation, fallback entries)
- Parallel scheduler with worker pool, depth-based priority (Beta/Alpha/Zeta),
  atomic claiming, dependency tracking, deduplication, and failure propagation
- Init-switch impact analysis: only rebuild packages using ${enabledinit}
- Init-agnostic service definitions: flat NamedService blocks replace
  per-init nesting
- Package conflicts: mutual incompatibility detection in resolver
- System groups: init-agnostic group creation in DSL
- Init-agnostic hostname/timezone: direct /etc/hostname and /etc/localtime writes
- Source tarball caching at /kappa/cache/ with atomic write-then-rename
- Package recipe caching with remote fetching and version comparison
- remotes = [...] block in system config for package repositories
- Auto-fetch: rebuild resolves missing packages from remotes
- uninstall phase in package definitions
- ${enabledinit} eval variable for init-conditional builds
- Shared util module (to_lower, shell_escape)
- 54 integration tests across two shell test suites
- Comprehensive README and CONTRIBUTING guide

Bug fixes from review:
- CRITICAL: Replace std::system() with fork+execvp (command injection)
- CRITICAL: Fix scheduler deadlock on successful completion
- CRITICAL: Fix rebuild init/kernel/bootloader change detection
- HIGH: Fix path traversal via unsanitized package names in cache
- HIGH: Fix TOCTOU race in cache write with atomic rename
- HIGH: Fix formatter dropping remotes/imports blocks
- HIGH: Fix formatter stripping empty-string assert values
- HIGH: Fix formatter non-idempotent output (sorted key iteration)
- HIGH: Populate ${enabledinit} from boot.init in BuildStep
- MEDIUM: Fix data race on non-atomic scheduler stop flag
- MEDIUM: Fix compute_depths() traversal direction
- MEDIUM: Add runit to doctor supported-init warning
- MEDIUM: Extract to_lower/shell_escape to shared kappa::util
- MEDIUM: Consolidate generator declarations in headers

src/config/eval.cpp

@@ -1,4 +1,7 @@
 #include "kappa/config/eval.hpp"
+#include "kappa/service/types.hpp"
+
+#include <iostream>
 
 namespace kappa::config {
 
@@ -55,26 +58,41 @@ std::vector<AssertFailure> evaluate_assertions(const dsl::SystemConfig& cfg) {
 
     return failures;
 }
-
-std::unordered_map<std::string, dsl::ServiceInit> resolve_services(
+std::unordered_map<std::string, dsl::NamedService> resolve_services(
     const dsl::SystemConfig& cfg,
     const std::unordered_map<std::string, dsl::PackageDef>& packages)
 {
-    std::unordered_map<std::string, dsl::ServiceInit> resolved;
+    std::unordered_map<std::string, dsl::NamedService> resolved;
     auto init_system = cfg.boot.init;
 
+    auto is = kappa::service::parse_init_system(init_system);
+    if (is == kappa::service::InitSystem::Unknown) {
+        std::cerr << "warning: unknown init system '" << init_system
+                  << "' — no services will be configured\n";
+        return {};
+    }
+
     for (auto& svc : cfg.services) {
         if (!svc.enable) { continue; }
 
-        auto pit = packages.find(svc.name);
+        // svc.name can be "postgresql" or "postgresql.checkpointer"
+        auto dot = svc.name.find('.');
+        auto pkg_name = (dot != std::string::npos)
+                        ? svc.name.substr(0, dot)
+                        : svc.name;
+        auto svc_name = (dot != std::string::npos)
+                        ? svc.name.substr(dot + 1)
+                        : std::string("main");
+
+        auto pit = packages.find(std::string(pkg_name));
         if (pit == packages.end()) { continue; }
 
         auto& pkg = pit->second;
-        if (pkg.service.empty()) { continue; }
-
-        auto it = pkg.service.find(init_system);
-        if (it != pkg.service.end()) {
-            resolved[svc.name] = it->second;
+        for (auto& ns : pkg.services) {
+            if (ns.name == svc_name) {
+                resolved[svc.name] = ns;
+                break;
+            }
         }
     }