Reorder npm diagnostic checks: project-specific before environment (#140)

* Initial plan

* Reorder diagnostic checks: package.json first, then npm/node

Co-authored-by: dermatz <6103201+dermatz@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: dermatz <6103201+dermatz@users.noreply.github.com>

Author: Copilot

src/Service/NodePackageManager.php

@@ -149,33 +149,33 @@ private function diagnoseAndReportNpmFailure(string $path, SymfonyStyle $io, \Ex
         $io->error('Failed to install node modules.');
         $io->newLine();
 
-        // Check 1: npm availability
+        // Check 1: package.json validity (project-specific, quick check)
+        if (!$this->isPackageJsonValid($path)) {
+            $io->error('package.json is missing or contains invalid JSON.');
+            $io->writeln('<fg=yellow>Fix:</>');
+            $sanitizedPath = preg_replace('/[[:cntrl:]]/', '', $path);
+            $io->writeln(
+                '  Verify package.json exists at: ' . $sanitizedPath . '/package.json'
+            );
+            return;
+        }
+
+        // Check 2: npm availability
         if (!$this->isCommandAvailable('npm')) {
             $io->error('npm is not installed or not available in PATH.');
             $io->writeln('<fg=yellow>Fix:</>');
             $io->writeln('  Install Node.js and npm: https://nodejs.org/');
             return;
         }
 
-        // Check 2: node availability
+        // Check 3: node availability
         if (!$this->isCommandAvailable('node')) {
             $io->error('Node.js is not installed or not available in PATH.');
             $io->writeln('<fg=yellow>Fix:</>');
             $io->writeln('  Install Node.js: https://nodejs.org/');
             return;
         }
 
-        // Check 3: package.json validity
-        if (!$this->isPackageJsonValid($path)) {
-            $io->error('package.json is missing or contains invalid JSON.');
-            $io->writeln('<fg=yellow>Fix:</>');
-            $sanitizedPath = preg_replace('/[[:cntrl:]]/', '', $path);
-            $io->writeln(
-                '  Verify package.json exists at: ' . $sanitizedPath . '/package.json'
-            );
-            return;
-        }
-
         // Check 4: package-lock.json corruption
         if ($this->fileDriver->isExists($path . '/package-lock.json')) {
             if (!$this->isPackageLockValid($path)) {