feat: system config DSL, services, CLI with rustc diagnostics

- System config parser (system/packages/services/boot/users blocks)
- Boot block: kernel, init, efi, swap, bootloader, root partition
- System-wide features, rollback config, swap partition
- Service block: per-init variants (runit, s6, etc.), system init selection via boot.init
- Feature-gated dependencies, config values accept numbers/bools/strings
- CLI: parse-package, parse-config, validate subcommands
- Rustc-style error diagnostics with source context, carets, help text
- Diagnostic module with ANSI color output

include/kappa/cli/diagnostic.hpp

@@ -0,0 +1,31 @@
+#pragma once
+
+#include <ostream>
+#include <string>
+#include <string_view>
+
+namespace kappa::cli {
+
+struct SourceLocation {
+    std::string_view file;
+    int line = 0;
+    int col  = 0;
+};
+
+void print_error(std::ostream& os,
+                 std::string_view source,
+                 SourceLocation loc,
+                 std::string_view message);
+
+void print_error(std::ostream& os,
+                 std::string_view source,
+                 SourceLocation loc,
+                 std::string_view message,
+                 std::string_view help);
+
+void print_note(std::ostream& os,
+                std::string_view source,
+                SourceLocation loc,
+                std::string_view message);
+
+} // namespace kappa::cli

include/kappa/dsl/ast.hpp

@@ -44,6 +44,14 @@ struct EnvEntry {
     bool soft = false;
 };
 
+struct ServiceInit {
+    std::string exec;
+    std::string type;
+    std::string user;
+    std::vector<int> ports;
+    std::unordered_map<std::string, std::string> env;
+};
+
 struct PackageDef {
     std::string name;
     std::string version;
@@ -56,6 +64,7 @@ struct PackageDef {
     std::vector<ConfigFile> config_files;
     std::vector<Patch> patches;
     std::vector<EnvEntry> env_entries;
+    std::unordered_map<std::string, ServiceInit> service;
     std::unordered_set<std::string> const_keys;
     Phase prepare;
     Phase build;

include/kappa/dsl/system.hpp

@@ -0,0 +1,64 @@
+#pragma once
+
+#include "kappa/dsl/ast.hpp"
+
+#include <string>
+#include <string_view>
+#include <unordered_map>
+#include <vector>
+
+namespace kappa::dsl {
+
+struct RollbackConfig {
+    int keep = 0;
+};
+
+struct SystemBlock {
+    std::string hostname;
+    std::string timezone;
+    std::vector<EnvEntry> env;
+    std::unordered_map<std::string, std::string> config;
+    std::unordered_map<std::string, FeatureDef> features;
+    RollbackConfig rollback;
+};
+
+struct PackageRef {
+    std::string name;
+    std::string version;
+    std::unordered_map<std::string, FeatureDef> features;
+    std::unordered_map<std::string, std::string> config;
+};
+
+struct BootBlock {
+    std::string kernel;
+    std::string init;
+    std::string efi;
+    std::string swap;
+    std::string bootloader;
+    std::unordered_map<std::string, std::string> params;
+};
+
+struct UserRef {
+    std::string name;
+    std::string shell;
+    std::vector<std::string> groups;
+    std::unordered_map<std::string, std::string> extra;
+};
+
+struct ServiceRef {
+    std::string name;
+    bool enable = false;
+    std::unordered_map<std::string, std::string> config;
+};
+
+struct SystemConfig {
+    SystemBlock system;
+    std::vector<PackageRef> packages;
+    std::vector<ServiceRef> services;
+    BootBlock boot;
+    std::vector<UserRef> users;
+};
+
+SystemConfig parse_system_config(std::string_view source);
+
+} // namespace kappa::dsl

include/kappa/dsl/token.hpp

@@ -34,6 +34,7 @@ enum class TokenType {
     KwLicense,
     KwPatches,
     KwEnv,
+    KwService,
     KwPrepare,
     KwBuild,
     KwCheck,