build: configure gemini cli to look for AGENTS.md

By default gemini cli looks for GEMINI.md, these settings change it to
consider AGENTS.md as well

(cherry picked from commit 85d6a2bc6e)

.gemini/settings.json

@@ -0,0 +1,5 @@
+{
+  "context": {
+    "fileName": ["AGENTS.md", "GEMINI.md"]
+  }
+}