fix: prevent command injection in Docker Compose parsing - add pre-save validation

This commit addresses a critical security issue where malicious Docker Compose
data was being saved to the database before validation occurred.

Problem:
- Service models were saved to database first
- Validation ran afterwards during parse()
- Malicious data persisted even when validation failed
- User saw error but damage was already done

Solution:
1. Created validateDockerComposeForInjection() to validate YAML before save
2. Added pre-save validation to all Service creation/update points:
   - Livewire: DockerCompose.php, StackForm.php
   - API: ServicesController.php (create, update, one-click)
3. Validates service names and volume paths (string + array formats)
4. Blocks shell metacharacters: backticks, $(), |, ;, &, >, <, newlines

Security fixes:
- Volume source paths (string format) - validated before save
- Volume source paths (array format) - validated before save
- Service names - validated before save
- Environment variable patterns - safe ${VAR} allowed, ${VAR:-$(cmd)} blocked

Testing:
- 60 security tests pass (176 assertions)
- PreSaveValidationTest.php: 15 tests for pre-save validation
- ValidateShellSafePathTest.php: 15 tests for core validation
- VolumeSecurityTest.php: 15 tests for volume parsing
- ServiceNameSecurityTest.php: 15 tests for service names

Related commits:
- Previous: Added validation during parse() phase
- This commit: Moves validation before database save

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

app/Livewire/Project/Service/StackForm.php

@@ -101,6 +101,10 @@ class StackForm extends Component
     {
         try {
             $this->validate();
+
+            // Validate for command injection BEFORE saving to database
+            validateDockerComposeForInjection($this->service->docker_compose_raw);
+
             $this->service->save();
             $this->service->saveExtraFields($this->fields);
             $this->service->parse();