refactor(core)!: rename Provider to LLMProvider and update implementations

- Export `LLMProvider` from `owlen-core` and replace public `Provider` re-exports.
- Convert `OllamaProvider` to implement the new `LLMProvider` trait with associated future types.
- Adjust imports and trait bounds in `remote_client.rs` to use the updated types.
- Add comprehensive provider interface tests (`provider_interface.rs`) verifying router routing and provider registry model listing with `MockProvider`.
- Align dependency versions across workspace crates by switching to workspace-managed versions.
- Extend CI (`.woodpecker.yml`) with a dedicated test step and generate coverage reports.
- Update architecture documentation to reflect the new provider abstraction.

crates/owlen-core/tests/provider_interface.rs

@@ -0,0 +1,43 @@
+use futures::StreamExt;
+use owlen_core::provider::test_utils::MockProvider;
+use owlen_core::{provider::ProviderRegistry, types::*, Router};
+use std::sync::Arc;
+
+fn request(message: &str) -> ChatRequest {
+    ChatRequest {
+        model: "mock-model".to_string(),
+        messages: vec![Message::new(Role::User, message.to_string())],
+        parameters: ChatParameters::default(),
+        tools: None,
+    }
+}
+
+#[tokio::test]
+async fn router_routes_to_registered_provider() {
+    let mut router = Router::new();
+    router.register_provider(MockProvider::default());
+    router.set_default_provider("mock".to_string());
+
+    let resp = router.chat(request("ping")).await.expect("chat succeeded");
+    assert_eq!(resp.message.content, "Mock response to: ping");
+
+    let mut stream = router
+        .chat_stream(request("pong"))
+        .await
+        .expect("stream returned");
+    let first = stream.next().await.expect("stream item").expect("ok item");
+    assert_eq!(first.message.content, "Mock response to: pong");
+}
+
+#[tokio::test]
+async fn registry_lists_models_from_all_providers() {
+    let mut registry = ProviderRegistry::new();
+    registry.register(MockProvider::default());
+    registry.register_arc(Arc::new(MockProvider::default()));
+
+    let models = registry.list_all_models().await.expect("listed");
+    assert!(
+        models.iter().any(|m| m.name == "mock-model"),
+        "expected mock-model in model list"
+    );
+}