feat: declare tool dependencies in package configs via tools field

- Add 'tools' field to ConfigValidator for build-time tool declarations
- Move jom and strawberry-perl from depends@windows to tools@windows in openssl.yml
- Move go-xcaddy/go-win from depends to tools in frankenphp.yml
- Register config/pkg/tool/ path in spc.registry.yml
- Use addInstallPackage for upx tool in php.php (ToolPackage instead of library dep)
- Include 'tool' type in DumpCapabilitiesCommand and InstallPackageCommand package lists

src/Package/Target/php.php

@@ -255,9 +255,11 @@ class php extends TargetPackage
             $installer->addBuildPackage('php-embed');
         }
 
-        // UPX compression: ensure the upx binary package is installed when requested
+        // UPX compression: ensure the upx tool package is installed when requested.
+        // upx is a ToolPackage now, so it's installed directly rather than added as a
+        // library dependency (tool packages bypass the DependencyResolver graph).
         if ($package->getBuildOption('with-upx-pack')) {
-            $additional_packages[] = 'upx';
+            $installer->addInstallPackage('upx');
         }
 
         return [...$extensions_pkg, ...$additional_packages];

src/StaticPHP/Command/Dev/DumpCapabilitiesCommand.php

@@ -54,8 +54,8 @@ class DumpCapabilitiesCommand extends BaseCommand
     {
         $result = [];
 
-        // library / target / virtual-target
-        foreach (PackageLoader::getPackages(['library', 'target', 'virtual-target']) as $name => $pkg) {
+        // library / target / virtual-target / tool
+        foreach (PackageLoader::getPackages(['library', 'target', 'virtual-target', 'tool']) as $name => $pkg) {
             $installable = [];
             $artifact = $pkg->getArtifact();
             if ($artifact !== null) {

src/StaticPHP/Command/InstallPackageCommand.php

@@ -23,7 +23,7 @@ class InstallPackageCommand extends BaseCommand
             'The package to install (name or path)',
             suggestedValues: function (CompletionInput $input) {
                 $packages = [];
-                foreach (PackageLoader::getPackages(['target', 'virtual-target']) as $name => $_) {
+                foreach (PackageLoader::getPackages(['target', 'virtual-target', 'tool']) as $name => $_) {
                     $packages[] = $name;
                 }
                 $val = $input->getCompletionValue();

src/StaticPHP/Config/ConfigValidator.php

@@ -24,6 +24,10 @@ class ConfigValidator
         'lang' => ConfigType::STRING,
         'frameworks' => ConfigType::LIST_ARRAY, // @
 
+        // build-time tool dependency declaration (resolved independently of the library
+        // dependency graph, see PackageInstaller::collectRequiredTools())
+        'tools' => ConfigType::LIST_ARRAY, // @
+
         // php-extension type fields
         'php-extension' => ConfigType::ASSOC_ARRAY,
         'zend-extension' => ConfigType::BOOL,
@@ -63,6 +67,9 @@ class ConfigValidator
         'lang' => false,
         'frameworks' => false, // @
 
+        // build-time tool dependency declaration
+        'tools' => false, // @
+
         // php-extension type fields
         'php-extension' => false,