add OCI GenAI game mention extraction function

sql/adb/80_sg_game_mention_extract.sql

@@ -0,0 +1,20 @@
+-- OCI GenAI chat extraction. This function returns JSON only; it never chooses tables.
+CREATE OR REPLACE FUNCTION sg_game_extract_mentions(p_question IN CLOB)
+  RETURN CLOB AUTHID DEFINER
+IS
+  v_prompt CLOB;
+  v_result CLOB;
+BEGIN
+  v_prompt := 'Extract only game-name mentions from the user question. '
+    || 'Return exactly one JSON object with keys game_mentions (array of strings) '
+    || 'and scope_hint (GLOBAL, SINGLE_GAME, MULTI_GAME, ALL_GAMES, UNKNOWN). '
+    || 'Do not resolve names to IDs and do not generate SQL. Question: '
+    || DBMS_LOB.SUBSTR(p_question, 4000, 1);
+  v_result := DBMS_CLOUD_AI.GENERATE(
+    prompt => v_prompt,
+    profile_name => 'SGMP_POC_OCI_GPT54MINI',
+    action => 'chat'
+  );
+  RETURN v_result;
+END;
+/