Add text-to-sql module: schema prompt through a restricted role, JSqlParser guard, read-only role with column grants and timeout, row cap, execution-based evaluation on a real PostgreSQL

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01JXVi2GMQ7bR5EmbUFdDj7N

README.md

@@ -21,3 +21,4 @@ Runnable companion code for the Spring AI articles on [ankurm.com](https://ankur
 
 Upgrading from Spring AI 1.x: [migration guide](https://ankurm.com/spring-ai-1-to-2-migration-guide/).
 | [`multimodal/`](multimodal) | A receipt image through `Media` and `ChatClient.entity(...)` into a Java record, on the real `OpenAiChatModel`, `AnthropicChatModel` and `OllamaChatModel` against a local server that OCRs the image it receives (so accuracy figures describe OCR, not any vision model). The same image on three wire formats, arithmetic validation and a repair retry, accuracy under tilt, shrinking and noise, and an image-token estimate from a documented formula. Spring Boot 4.1.1, Spring AI 2.0.1, Java 25. | [Multimodal Spring AI: Extract Structured Data from Images](https://ankurm.com/multimodal-spring-ai-extract-structured-data-from-images-receipts-java-records/) |
+| [`text-to-sql/`](text-to-sql) | A question to SQL to rows, safely, on a real PostgreSQL 16: a schema prompt built through the restricted role, a JSqlParser guard (one statement, SELECT only, listed tables and functions), a read-only role with column grants and a statement timeout, a row cap, and evaluation by comparing results. Sixteen queries against four setups (13 harmful: 13 succeed with neither protection, 0 with both). The model is a script, not a language model. Spring Boot 4.1.1, Spring AI 2.0.1, Java 25. | [Text-to-SQL with Spring AI, Done Safely](https://ankurm.com/text-to-sql-spring-ai-read-only-roles-query-validation/) |