refactor(ollama)!: remove Ollama provider crate and implementation

Deletes the `owlen-ollama` Cargo.toml and source files, fully removing the Ollama provider from the workspace. This aligns the project with the MCP‑only architecture and eliminates direct provider dependencies.

crates/owlen-core/src/lib.rs

@@ -15,6 +15,7 @@ pub mod mcp;
 pub mod mode;
 pub mod model;
 pub mod provider;
+pub mod providers;
 pub mod router;
 pub mod sandbox;
 pub mod session;
@@ -43,6 +44,7 @@ pub use mode::*;
 pub use model::*;
 // Export provider types but exclude test_utils to avoid ambiguity
 pub use provider::{ChatStream, LLMProvider, Provider, ProviderConfig, ProviderRegistry};
+pub use providers::*;
 pub use router::*;
 pub use sandbox::*;
 pub use session::*;