refactor: Remove unused NutritionAdvisor agent

The NutritionAdvisor agent was superseded by AssistantAgent which is
now bound to the Advisor interface. This cleanup removes the unused
NutritionAdvisor class and updates all references to use AssistantAgent.

Changes:
- Delete app/Ai/Agents/NutritionAdvisor.php
- Update HistoryFactory default agent to AssistantAgent
- Update HistoryTest to expect AssistantAgent as default
- Update ProcessAdvisorMessageActionTest to use AssistantAgent

Author: tuvshinjargal

app/Ai/Agents/NutritionAdvisor.php

@@ -29,7 +29,7 @@ public function definition(): array
             'id' => (string) Str::uuid7(),
             'conversation_id' => Conversation::factory(),
             'user_id' => User::factory(),
-            'agent' => \App\Ai\Agents\NutritionAdvisor::class,
+            'agent' => \App\Ai\Agents\AssistantAgent::class,
             'role' => fake()->randomElement([MessageRole::User, MessageRole::Assistant]),
             'content' => fake()->paragraph(),
             'attachments' => [],

database/factories/HistoryFactory.php

@@ -3,12 +3,12 @@
 declare(strict_types=1);
 
 use App\Actions\ProcessAdvisorMessageAction;
-use App\Ai\Agents\NutritionAdvisor;
+use App\Ai\Agents\AssistantAgent;
 use App\Models\User;
 use Laravel\Ai\Contracts\ConversationStore;
 
 it('creates new conversation when none exists', function (): void {
-    NutritionAdvisor::fake(['Hello!']);
+    AssistantAgent::fake(['Hello!']);
 
     $conversationStore = mock(ConversationStore::class);
     $conversationStore
@@ -24,7 +24,7 @@
         ->andReturn('conv-123');
 
     $action = new ProcessAdvisorMessageAction(
-        resolve(NutritionAdvisor::class),
+        resolve(AssistantAgent::class),
         $conversationStore,
     );
 
@@ -33,14 +33,14 @@
 
     expect($result['response'])->toBe('Hello!');
     expect($result['conversation_id'])->toBe('conv-123');
-    NutritionAdvisor::assertPrompted('Test message');
+    AssistantAgent::assertPrompted('Test message');
 });
 
 it('uses existing conversation when provided', function (): void {
-    NutritionAdvisor::fake(['Continuing...']);
+    AssistantAgent::fake(['Continuing...']);
 
     $action = new ProcessAdvisorMessageAction(
-        resolve(NutritionAdvisor::class),
+        resolve(AssistantAgent::class),
         resolve(ConversationStore::class),
     );
 
@@ -52,7 +52,7 @@
 });
 
 it('reuses latest conversation when no id provided but exists', function (): void {
-    NutritionAdvisor::fake(['Reusing!']);
+    AssistantAgent::fake(['Reusing!']);
 
     $conversationStore = mock(ConversationStore::class);
     $conversationStore
@@ -62,7 +62,7 @@
         ->andReturn('latest-conv');
 
     $action = new ProcessAdvisorMessageAction(
-        resolve(NutritionAdvisor::class),
+        resolve(AssistantAgent::class),
         $conversationStore,
     );
 
@@ -82,7 +82,7 @@
         ->andReturn('new-conv');
 
     $action = new ProcessAdvisorMessageAction(
-        resolve(NutritionAdvisor::class),
+        resolve(AssistantAgent::class),
         $conversationStore,
     );
 

tests/Unit/Actions/ProcessAdvisorMessageActionTest.php

@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-use App\Ai\Agents\NutritionAdvisor;
+use App\Ai\Agents\AssistantAgent;
 use App\Models\Conversation;
 use App\Models\History;
 use App\Models\User;
@@ -73,10 +73,10 @@
         ->and($history->meta)->toBeArray()->toHaveKey('key');
 });
 
-it('defaults agent to NutritionAdvisor', function (): void {
+it('defaults agent to AssistantAgent', function (): void {
     $history = History::factory()->create();
 
-    expect($history->agent)->toBe(NutritionAdvisor::class);
+    expect($history->agent)->toBe(AssistantAgent::class);
 });
 
 it('can set custom agent', function (): void {