feat(forms): make textarea monospace opt-in and improve multiline toggle

Add `monospace` prop to Textarea component so font-mono is no longer
applied by default. Apply it explicitly to env variable editors, private
key fields, and shared variable forms where monospace is appropriate.

Use Alpine.js x-data/x-model to make the multiline toggle reactive
without a full Livewire round-trip. Add wire:key on the input/textarea
wrappers to force proper DOM replacement when switching modes.

resources/views/livewire/shared-variables/project/show.blade.php

@@ -28,7 +28,7 @@
         </div>
     @else
         <form wire:submit='submit' class="flex flex-col gap-2">
-            <x-forms.textarea canGate="update" :canResource="$project" rows="20" class="whitespace-pre-wrap" id="variables" wire:model="variables"
+            <x-forms.textarea canGate="update" :canResource="$project" rows="20" class="whitespace-pre-wrap" id="variables" wire:model="variables" monospace
                 label="Project Shared Variables"></x-forms.textarea>
             <x-forms.button canGate="update" :canResource="$project" type="submit" class="btn btn-primary">Save All Environment Variables</x-forms.button>
         </form>