fix: prevent hybrid mode from leaking OpenRouter model to local llamacpp client

When backend=hybrid with LLM_BACKEND=llamacpp, the user-selected model
(an OpenRouter id like "google/gemini-3-flash-preview") was being applied
to the local LlamaCppClient's primary_model and vision_model. This caused
describe_image to send the OpenRouter model name to llama-swap, which
returned 400 because it has no such slot.

Guard the local-client model override with !is_hybrid so it only applies
in local-only mode (where the user is selecting a different local model).
Bump to v1.2.0.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/ai/mod.rs

@@ -25,11 +25,11 @@ pub use handlers::{
     get_insight_handler, get_openrouter_models_handler, rate_insight_handler,
 };
 pub use insight_generator::InsightGenerator;
+pub use llamacpp::LlamaCppClient;
 #[allow(unused_imports)]
 pub use llm_client::{
     ChatMessage, LlmClient, ModelCapabilities, Tool, ToolCall, ToolCallFunction, ToolFunction,
 };
-pub use llamacpp::LlamaCppClient;
 pub use ollama::{EMBEDDING_MODEL, OllamaClient};
 pub use sms_client::{SmsApiClient, SmsMessage};