Add free-text api_instructions field to Sites

For custom sites we'll post to via their own API — there's no wired-in
publisher for these, so this is where the site owner documents how to
actually post there (auth, endpoints, payload shape). Shown in the UI
for non-WordPress sites, exposed via the JSON API, and pointed to from
AI_API.md's "any other network/CMS" fallback section so an agent checks
it before improvising.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/Http/Resources/SiteResource.php

@@ -17,6 +17,7 @@ class SiteResource extends JsonResource
             'cms_type' => $this->cms_type,
             'wp_username' => $this->wp_username,
             'wp_app_password' => $this->wp_app_password,
+            'api_instructions' => $this->api_instructions,
             'created_at' => $this->created_at,
             'updated_at' => $this->updated_at,
         ];

app/Livewire/Sites/Index.php

@@ -27,6 +27,8 @@ class Index extends Component
 
     public string $wpAppPassword = '';
 
+    public ?string $apiInstructions = null;
+
     public function render()
     {
         return view('livewire.sites.index', [
@@ -51,6 +53,7 @@ class Index extends Component
         $this->cmsType = $site->cms_type;
         $this->wpUsername = $site->wp_username ?? '';
         $this->wpAppPassword = $site->wp_app_password ?? '';
+        $this->apiInstructions = $site->api_instructions;
         $this->showForm = true;
     }
 
@@ -63,6 +66,7 @@ class Index extends Component
             'cmsType' => ['required', 'string', 'in:' . implode(',', Site::CMS_TYPES)],
             'wpUsername' => ['required_if:cmsType,wordpress', 'nullable', 'string', 'max:255'],
             'wpAppPassword' => ['required_if:cmsType,wordpress', 'nullable', 'string', 'max:255'],
+            'apiInstructions' => ['nullable', 'string'],
         ]);
 
         Site::updateOrCreate(['id' => $this->editingId], [
@@ -72,6 +76,7 @@ class Index extends Component
             'cms_type' => $validated['cmsType'],
             'wp_username' => $validated['cmsType'] === 'wordpress' ? $validated['wpUsername'] : null,
             'wp_app_password' => $validated['cmsType'] === 'wordpress' ? $validated['wpAppPassword'] : null,
+            'api_instructions' => $validated['apiInstructions'],
         ]);
 
         $this->resetForm();
@@ -97,6 +102,7 @@ class Index extends Component
         $this->cmsType = 'custom';
         $this->wpUsername = '';
         $this->wpAppPassword = '';
+        $this->apiInstructions = null;
         $this->resetValidation();
     }
 }

app/Models/Site.php

@@ -18,5 +18,6 @@ class Site extends Model
         'cms_type',
         'wp_username',
         'wp_app_password',
+        'api_instructions',
     ];
 }