Fix: Add .env to .gitignore and create .env.example

- Uncomment .env in .gitignore to prevent accidental commits
- Remove .env from git tracking
- Add .env.example with placeholder values for documentation
- Fixes security issue where .env was committed with credentials

.env.example

@@ -0,0 +1,8 @@
+# Supabase Configuration
+# Copy this file to .env and fill in your actual values
+
+# Supabase API URL
+VITE_SUPABASE_URL=http://localhost:8000
+
+# Supabase anonymous key (public)
+VITE_SUPABASE_ANON_KEY=your-anon-key-here