Migrate to unified skills architecture, add Copilot & Antigravity (v2.0.0)

All commands are now skills with user-invokable: true. Source lives in
source/skills/{name}/SKILL.md. Added VS Code Copilot (.agents/skills/)
and Google Antigravity (.agent/skills/) transformers. All 6 providers
output to skills directories only — no more commands/prompts dirs.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

scripts/lib/zip.js

@@ -1,6 +1,6 @@
 /**
  * ZIP Generation Utilities
- * 
+ *
  * Creates ZIP bundles for each provider's distribution
  */
 
@@ -17,27 +17,27 @@ import { existsSync, readdirSync, statSync } from 'fs';
 export async function createProviderZip(providerDir, distDir, providerName) {
   const zipFileName = `${providerName}.zip`;
   const zipPath = path.join(distDir, zipFileName);
-  
+
   // Check if provider directory exists
   if (!existsSync(providerDir)) {
     console.warn(`⚠️  Provider directory not found: ${providerDir}`);
     return;
   }
-  
+
   // Remove existing zip if present
   if (existsSync(zipPath)) {
     await $`rm ${zipPath}`.quiet();
   }
-  
+
   try {
     // Create zip using bun's shell
     // cd into provider dir and zip all contents
     await $`cd ${providerDir} && zip -r ../${zipFileName} . -x "*.DS_Store"`.quiet();
-    
+
     // Get file size for reporting
     const stats = statSync(zipPath);
     const sizeMB = (stats.size / 1024 / 1024).toFixed(2);
-    
+
     console.log(`  📦 ${zipFileName} (${sizeMB} MB)`);
   } catch (error) {
     console.error(`  ❌ Failed to create ${zipFileName}:`, error.message);
@@ -51,7 +51,7 @@ export async function createProviderZip(providerDir, distDir, providerName) {
 export async function createAllZips(distDir) {
   console.log('\n📦 Creating ZIP bundles...');
 
-  const providers = ['cursor', 'claude-code', 'gemini', 'codex'];
+  const providers = ['cursor', 'claude-code', 'gemini', 'codex', 'copilot', 'antigravity'];
 
   // Create unprefixed ZIPs
   for (const provider of providers) {
@@ -66,4 +66,3 @@ export async function createAllZips(distDir) {
     await createProviderZip(providerDir, distDir, `${provider}-prefixed`);
   }
 }
-