fix(gemini): preserve 'pattern' in antigravity tool schema translation

Remove "pattern" from UNSUPPORTED_SCHEMA_CONSTRAINTS so glob/grep tool
schemas keep the required "pattern" property for the antigravity provider.

Fixes decolua/9router#1368

Co-authored-by: Cursor <cursoragent@cursor.com>

open-sse/translator/formats/gemini.js

@@ -7,7 +7,7 @@ import { OPENAI_BLOCK } from "../schema/index.js";
 export const UNSUPPORTED_SCHEMA_CONSTRAINTS = [
   // Basic constraints (not supported by Gemini API)
   "minLength", "maxLength", "exclusiveMinimum", "exclusiveMaximum",
-  "pattern", "minItems", "maxItems", "format",
+  "minItems", "maxItems", "format",
   // Claude rejects these in VALIDATED mode
   "default", "examples",
   // JSON Schema meta keywords