fix(env): validate Docker-compatible variable keys

Add shared environment variable key validation and normalization for Livewire forms and models, allowing Docker-compatible keys while rejecting invalid entries such as keys containing equals signs. Also quote Railpack build environment and secret arguments safely.

app/Models/SharedEnvironmentVariable.php

@@ -2,6 +2,8 @@
 
 namespace App\Models;
 
+use App\Support\ValidationPatterns;
+use Illuminate\Database\Eloquent\Casts\Attribute;
 use Illuminate\Database\Eloquent\Model;
 
 class SharedEnvironmentVariable extends Model
@@ -33,6 +35,13 @@ class SharedEnvironmentVariable extends Model
         'value' => 'encrypted',
     ];
 
+    protected function key(): Attribute
+    {
+        return Attribute::make(
+            set: fn (string $value) => ValidationPatterns::validatedEnvironmentVariableKey($value),
+        );
+    }
+
     public function team()
     {
         return $this->belongsTo(Team::class);