refactor: restructure tool target configs into tool package system

- Move tool configs from config/pkg/target/ to config/pkg/tool/
- Add ToolVersionRegistry for tracking installed tool versions
- Delete old Target/pkgconfig.php, move to tool config
- Rename: 7za-win, go-win, go-xcaddy, jom, nasm, protoc, strawberry-perl, upx, vswhere, zig, pkg-config

src/StaticPHP/Package/ToolVersionRegistry.php

@@ -0,0 +1,79 @@
+<?php
+
+declare(strict_types=1);
+
+namespace StaticPHP\Package;
+
+use StaticPHP\Runtime\SystemTarget;
+
+/**
+ * Tracks the version actually installed on disk for tool packages (PKG_ROOT_PATH), separate from
+ * the download cache (ArtifactCache). Tools are installed once and reused across many builds, so
+ * the download cache (which only reflects the last download) can drift from what's really on disk
+ * (e.g. cache cleared, or installed a long time ago via `doctor`). This registry is the source of
+ * truth for "what version is currently installed", used by ToolPackage::getInstalledVersion() and
+ * the `check-update --installed` flag.
+ *
+ * Backed by a small JSON file at PKG_ROOT_PATH/.spc-tool-versions.json, mirroring the same
+ * read-once/write-through pattern used by StaticPHP\Artifact\ArtifactCache.
+ */
+class ToolVersionRegistry
+{
+    /** @var null|array<string, array{version: null|string, platform: string, installed_at: string}> */
+    private static ?array $data = null;
+
+    /**
+     * Get the recorded installed version for a tool, or null if never recorded (not a tool
+     * package, not installed yet, or the artifact doesn't expose a version).
+     */
+    public static function get(string $tool_name): ?string
+    {
+        self::load();
+        return self::$data[$tool_name]['version'] ?? null;
+    }
+
+    /**
+     * Record the version currently installed for a tool. Called after a tool package's binary
+     * has been (re-)installed, regardless of whether extraction actually ran (keeps the registry
+     * self-healing if it was deleted separately from the installed files).
+     */
+    public static function record(string $tool_name, ?string $version): void
+    {
+        self::load();
+        self::$data[$tool_name] = [
+            'version' => $version,
+            'platform' => SystemTarget::getCurrentPlatformString(),
+            'installed_at' => date('c'),
+        ];
+        self::save();
+    }
+
+    private static function getPath(): string
+    {
+        return PKG_ROOT_PATH . '/.spc-tool-versions.json';
+    }
+
+    private static function load(): void
+    {
+        if (self::$data !== null) {
+            return;
+        }
+        $path = self::getPath();
+        if (!file_exists($path)) {
+            self::$data = [];
+            return;
+        }
+        $content = file_get_contents($path);
+        self::$data = is_string($content) ? (json_decode($content, true) ?: []) : [];
+    }
+
+    private static function save(): void
+    {
+        $path = self::getPath();
+        $dir = dirname($path);
+        if (!is_dir($dir)) {
+            @mkdir($dir, 0755, true);
+        }
+        file_put_contents($path, json_encode(self::$data, JSON_UNESCAPED_SLASHES | JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE));
+    }
+}