Rename OpenAIProcessorConversationConfig DB model to more apt AiModelApi (#998)

* Rename OpenAIProcessorConversationConfig to more apt AiModelAPI

The DB model name had drifted from what it is being used for,
a general chat api provider that supports other chat api providers like
anthropic and google chat models apart from openai based chat models.

This change renames the DB model and updates the docs to remove this
confusion.

Using Ai Model Api we catch most use-cases including chat, stt, image generation etc.

tests/helpers.py

@@ -5,11 +5,11 @@ import factory
 from django.utils.timezone import make_aware
 
 from khoj.database.models import (
+    AiModelApi,
     ChatModelOptions,
     Conversation,
     KhojApiUser,
     KhojUser,
-    OpenAIProcessorConversationConfig,
     ProcessLock,
     SearchModelConfig,
     Subscription,
@@ -76,9 +76,9 @@ class ApiUserFactory(factory.django.DjangoModelFactory):
     token = factory.Faker("password")
 
 
-class OpenAIProcessorConversationConfigFactory(factory.django.DjangoModelFactory):
+class AiModelApiFactory(factory.django.DjangoModelFactory):
     class Meta:
-        model = OpenAIProcessorConversationConfig
+        model = AiModelApi
 
     api_key = get_chat_api_key()
 
@@ -91,9 +91,7 @@ class ChatModelOptionsFactory(factory.django.DjangoModelFactory):
     tokenizer = None
     chat_model = "bartowski/Meta-Llama-3.2-3B-Instruct-GGUF"
     model_type = get_chat_provider()
-    openai_config = factory.LazyAttribute(
-        lambda obj: OpenAIProcessorConversationConfigFactory() if get_chat_api_key() else None
-    )
+    ai_model_api = factory.LazyAttribute(lambda obj: AiModelApiFactory() if get_chat_api_key() else None)
 
 
 class UserConversationProcessorConfigFactory(factory.django.DjangoModelFactory):