Duplicate graph-schema component to bigquery skill

PiperOrigin-RevId: 938638773

Author: Data Cloud Agents Team

skills/developing-with-bigquery/SKILL.md skills/bigquery/SKILL.mdskills/developing-with-bigquery/SKILL.md renamed to skills/bigquery/SKILL.md

@@ -1,5 +1,5 @@
 ---
-name: developing-with-bigquery
+name: bigquery
 description: |
   Provides BigQuery-specific logic, knowledge, and specialized standards.
   Use this skill whenever you are doing anything with BigQuery, including:
@@ -9,17 +9,14 @@ description: |
     4. Graph Analytics (GQL & Property Graphs)
 license: Apache-2.0
 metadata:
-  version: v2
+  version: v4
   publisher: google
+
 ---
 
 This skill provides comprehensive guidance for BigQuery services, optimizations,
 and data handling. It acts as a routing table for specialized BigQuery topics.
 
-> [!IMPORTANT]
->
-> For general standards on running BigQuery in notebooks (SQL cells, `export`
-> keyword), see `@skill:notebook-guidance`.
 
 > [!IMPORTANT]
 >
@@ -33,12 +30,14 @@ features:
 
 Performance and efficiency guidelines for BigQuery SQL. Includes rules for
 column pruning, pushdown, and materialization strategies.
+
 - **Guide**: [OPTIMIZATION.md](references/sql/OPTIMIZATION.md)
 
 ### 2. BigFrames (BigQuery DataFrames)
 
 Guidelines for generating valid BigFrames code for data manipulation, model
 development, and visualization.
+
 - **Guide**: [BIGFRAMES.md](references/bigframes/BIGFRAMES.md)
 
 Bigframes should be the default library/tool as it is more efficient than using
@@ -48,6 +47,7 @@ the BigQuery Python client library.
 
 Usage rules and syntax standards for all BigQuery AI/ML functions via SQL
 (Forecasting, Generative AI, Classification, etc.).
+
 - **Best Practices**: [ai_function_best_practices.md](references/ai-ml/ai_function_best_practices.md)
 - **Functions Reference**:
 
@@ -70,5 +70,10 @@ Usage rules and syntax standards for all BigQuery AI/ML functions via SQL
 ### 4. Graph Analytics (Property Graphs & GQL)
 
 Guidelines and best practices for querying property graphs in BigQuery.
+
 - **Property Graph Guidelines**: [graph_queries.md](references/graph/graph_queries.md) - Standard GQL syntax and query patterns.
 - **Semantic Graph Guidelines**: [semantic_queries.md](references/graph/semantic_queries.md) - Semantic graph operations and expand functions.
+-   **Graph Schema DDL Advisor**:
+    [graph_schema_ddl_advisor.md](references/graph/graph-schema/graph_schema_ddl_advisor.md)
+    -   Assists in defining, correcting, and optimizing BigQuery Property Graph
+        and Semantic Graph schemas.