Row embeddings APIs exposed (#646)

* Added row embeddings API and CLI support

* Updated protocol specs

* Row embeddings agent tool

* Add new agent tool to CLI

specs/api/components/schemas/embeddings-query/RowEmbeddingsQueryRequest.yaml

@@ -0,0 +1,39 @@
+type: object
+description: |
+  Row embeddings query request - find similar rows by vector similarity on indexed fields.
+  Enables semantic/fuzzy matching on structured data.
+required:
+  - vectors
+  - schema_name
+properties:
+  vectors:
+    type: array
+    description: Query embedding vector
+    items:
+      type: number
+    example: [0.023, -0.142, 0.089, 0.234, -0.067, 0.156]
+  schema_name:
+    type: string
+    description: Schema name to search within
+    example: customers
+  index_name:
+    type: string
+    description: Optional index name to filter search to specific index
+    example: full_name
+  limit:
+    type: integer
+    description: Maximum number of matches to return
+    default: 10
+    minimum: 1
+    maximum: 1000
+    example: 20
+  user:
+    type: string
+    description: User identifier
+    default: trustgraph
+    example: alice
+  collection:
+    type: string
+    description: Collection to search
+    default: default
+    example: sales