example: set echo table-in-out function tags (category/type)

The shared integration suite (function_registration.test) asserts the example
worker's `echo` function exposes tags category=debug, type=passthrough via
duckdb_functions().tags. Set them now that per-function tags are supported.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: rustyconover

vgi-example-worker/src/main/java/farm/query/vgi/example/tableinout/EchoFunction.java

@@ -29,7 +29,9 @@ public final class EchoFunction extends PassthroughTIOFunction {
         // stays off — the InOut path always runs filters via a FILTER node.
         return FunctionMetadata.describe("Passthrough function that emits each input batch unchanged")
                 .withPushdown(true, false, false)
-                .withCategories("utility", "debug");
+                .withCategories("utility", "debug")
+                .withTag("category", "debug")
+                .withTag("type", "passthrough");
     }
 
     @Override public List<ArgSpec> argumentSpecs() {