fix(modpack-checker): Code review fixes — license, safety, and polish

Fixes 10 issues from full code review:
- License corrected from MIT to Commercial
- Deprecated datetime.utcnow() replaced with timezone-aware alternative
- PHP array bounds checks added for all platform API responses
- Modrinth file detection now derives project slug instead of using MC version
- validate_api_key() no longer swallows network errors
- HTTP timeouts added to all external API calls in PHP
- Empty API key rejection added to CLI
- Corrupted config now warns on stderr instead of failing silently
- Error response format made consistent across controller
- Docs updated with correct repo URL and clearer CurseForge ID instructions

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

services/modpack-version-checker/blueprint-extension/app/Http/Controllers/ModpackAPIController.php

@@ -103,7 +103,9 @@ class ModpackAPIController extends Controller
         if (empty($platform) || empty($modpackId)) {
             return response()->json([
                 'success' => false,
-                'message' => 'Could not detect modpack. Set MODPACK_PLATFORM and MODPACK_ID in startup variables.',
+                'platform' => $platform ?? null,
+                'modpack_id' => $modpackId ?? null,
+                'error' => 'Could not detect modpack. Set MODPACK_PLATFORM and MODPACK_ID in startup variables.',
             ]);
         }
 
@@ -174,9 +176,12 @@ class ModpackAPIController extends Controller
             if ($modrinthIndex) {
                 $data = json_decode($modrinthIndex, true);
                 if (isset($data['formatVersion'])) {
+                    // Use the pack name as the Modrinth project slug for API lookups.
+                    // dependencies.minecraft is a MC version (e.g. "1.20.1"), NOT a project ID.
+                    $slug = isset($data['name']) ? strtolower(str_replace(' ', '-', $data['name'])) : null;
                     return [
                         'platform' => 'modrinth',
-                        'modpack_id' => $data['dependencies']['minecraft'] ?? null,
+                        'modpack_id' => $slug,
                         'name' => $data['name'] ?? null,
                         'version' => $data['versionId'] ?? null,
                     ];