Fix: yarn.lock symlink issue in Docker build

- Updated Dockerfile.simple to handle yarn.lock correctly
- Added script in deploy-simple.sh to convert symlink to real file
- Updated .gitignore to ignore converted yarn.lock
- This fixes the 'yarn.lock not found' error during Docker build

.gitignore

@@ -1,8 +1,5 @@
+# Dependencies
 **/node_modules
-.next
-.cache
-.build
-*.nfs*
 **/.yarn/
 !**/.yarn/patches
 !**/.yarn/plugins
@@ -12,12 +9,36 @@
 !**/.yarn/cache
 **/.yarn/build-state.yml
 **/.yarn/install-state.gz
+
+# Next.js
+.next
+.cache
+.build
 dist
 target
 out
+*.tsbuildinfo
+
+# Environment variables (CRITICAL - never commit!)
+.env
+.env.local
+.env.production
+.env.*.local
+
+# Docker generated files
+docker-compose.simple.yml
+
+# Yarn lockfile (if converted from symlink during Docker build)
+nextjs_space/yarn.lock
+
+# Logs
 .deploy
 .logs
-*.tsbuildinfo
+*.nfs*
 npm-debug.log*
 yarn-debug.log*
 yarn-error.log*
+
+# OS files
+.DS_Store
+Thumbs.db