fix(memory): add openrouter as recognized embedding provider

The embedding provider factory only recognized "openai" and "custom:*",
causing "openrouter" to silently fall through to NoopEmbedding. This
made vector/semantic search completely non-functional — memory recall
fell back to BM25 keyword-only matching, with 70% of the hybrid score
always returning zero.

Route "openrouter" through OpenAiEmbedding with the OpenRouter API base
URL (https://openrouter.ai/api/v1), which is OpenAI-compatible.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/memory/embeddings.rs

@@ -172,6 +172,15 @@ pub fn create_embedding_provider(
                 dims,
             ))
         }
+        "openrouter" => {
+            let key = api_key.unwrap_or("");
+            Box::new(OpenAiEmbedding::new(
+                "https://openrouter.ai/api/v1",
+                key,
+                model,
+                dims,
+            ))
+        }
         name if name.starts_with("custom:") => {
             let base_url = name.strip_prefix("custom:").unwrap_or("");
             let key = api_key.unwrap_or("");
@@ -212,6 +221,18 @@ mod tests {
         assert_eq!(p.dimensions(), 1536);
     }
 
+    #[test]
+    fn factory_openrouter() {
+        let p = create_embedding_provider(
+            "openrouter",
+            Some("sk-or-test"),
+            "openai/text-embedding-3-small",
+            1536,
+        );
+        assert_eq!(p.name(), "openai"); // uses OpenAiEmbedding internally
+        assert_eq!(p.dimensions(), 1536);
+    }
+
     #[test]
     fn factory_custom_url() {
         let p = create_embedding_provider("custom:http://localhost:1234", None, "model", 768);
@@ -281,6 +302,20 @@ mod tests {
         assert_eq!(p.dimensions(), 384);
     }
 
+    #[test]
+    fn embeddings_url_openrouter() {
+        let p = OpenAiEmbedding::new(
+            "https://openrouter.ai/api/v1",
+            "key",
+            "openai/text-embedding-3-small",
+            1536,
+        );
+        assert_eq!(
+            p.embeddings_url(),
+            "https://openrouter.ai/api/v1/embeddings"
+        );
+    }
+
     #[test]
     fn embeddings_url_standard_openai() {
         let p = OpenAiEmbedding::new("https://api.openai.com", "key", "model", 1536);