Extend Camino edge endpoint protocol

proto/camino/schema.proto

@@ -25,6 +25,7 @@ enum Cardinality {
   MANY = 3;
   MANY_UNIQUE = 4;
   MANY_ORDERED = 5;
+  MANY_UNIQUE_ORDERED = 6;
 }
 
 enum DocRefStrength {
@@ -147,12 +148,26 @@ message FieldOps {
 
 message EdgeSchema {
   SymbolRef id = 1;
+  // Legacy/source-side projection fields. Prefer from_endpoint/to_endpoint.
   string source_field = 2;
   SymbolRef from_class = 3;
   SymbolRef to_class = 4;
   Cardinality cardinality = 5;
   string inverse = 6;
   repeated FieldSchema fields = 7;
+  EdgeEndpointSchema from_endpoint = 8;
+  EdgeEndpointSchema to_endpoint = 9;
+  SymbolRef declaring_class = 10;
+  repeated SymbolRef tags = 11;
+  repeated SymbolRef implements = 12;
+}
+
+message EdgeEndpointSchema {
+  SymbolRef class = 1;
+  SymbolRef interface = 2;
+  string projection = 3;
+  Cardinality cardinality = 4;
+  bool indexed = 5;
 }
 
 message MethodSchema {