feat(compiler): replace hardcoded autoloader path with dynamic resolution

- Replace direct require of TYPEPHP_ROOT_PATH . '/vendor/autoload.php' with resolveComposerAutoloader() function
- Add new resolveComposerAutoloader() function to locate Composer autoloader from multiple candidate paths
- Support both source checkout and packaged SDK environments by checking TYPEPHP_ROOT_PATH and PHP_HOME
- Implement fallback mechanism to search for vendor/autoload.php in different locations
- Add detailed error reporting when autoloader is not found with specific search paths
- Include installation instructions in error output when dependencies are missing
- Exit with error code 1 when autoloader cannot be located

src/compiler.php

@@ -32,7 +32,7 @@ function main(int $argc, array $argv): void
     // in bin/bootstrap.php. The AOT compiler starts here directly and therefore
     // must load the dependencies packaged alongside tpc itself.
     if (!defined('TYPEPHP_PHP_SCRIPT_ENTRY')) {
-        require_once TYPEPHP_ROOT_PATH . '/vendor/autoload.php';
+        require_once resolveComposerAutoloader();
     }
 
     $completionStatus = CompletionCommand::execute($argv);
@@ -136,6 +136,43 @@ function main(int $argc, array $argv): void
     }
 }
 
+/**
+ * Locate the Composer autoloader that ships with the compiler.
+ *
+ * A source checkout and a Unix-like package keep it below TYPEPHP_ROOT_PATH,
+ * while a packaged SDK extracts it below PHP_HOME.
+ */
+function resolveComposerAutoloader(): string
+{
+    $candidates = [];
+    $roots = [TYPEPHP_ROOT_PATH, getenv('PHP_HOME') ?: null];
+    foreach ($roots as $root) {
+        if (!is_string($root) || $root === '') {
+            continue;
+        }
+        $candidate = rtrim($root, '/\\') . '/vendor/autoload.php';
+        if (!in_array($candidate, $candidates, true)) {
+            $candidates[] = $candidate;
+        }
+    }
+
+    foreach ($candidates as $candidate) {
+        if (is_file($candidate)) {
+            return $candidate;
+        }
+    }
+
+    fwrite(STDERR, "Unable to find the Composer autoloader (vendor/autoload.php).\n");
+    fwrite(STDERR, "Searched in:\n");
+    foreach ($candidates as $candidate) {
+        fwrite(STDERR, "  - {$candidate}\n");
+    }
+    fwrite(STDERR, "\nInstall the TypePHP dependencies with Composer first:\n");
+    fwrite(STDERR, "  cd " . TYPEPHP_ROOT_PATH . " && composer install\n");
+    fwrite(STDERR, "Or point PHP_HOME at a TypePHP installation that already contains vendor/autoload.php.\n");
+    exit(1);
+}
+
 function shouldCompileNativeSourceProject(array $argv): bool
 {
     foreach (array_slice($argv, 1) as $argument) {