Add mini_audit_pro asynchronous audit logging extension

[tanyang-star]

Motivation

• Provide a lightweight asynchronous auditing extension that captures DML and DDL for selected tables and writes audit events to a persistent mini_audit_log table.
• Avoid synchronous writes inside hooks by using a shared-memory ring queue and a background worker to batch-flush events via SPI.

Description

• Add a new contrib extension mini_audit_pro with build support by updating contrib/Makefile and adding contrib/mini_audit_pro/Makefile and .control files.
• Implement the extension core in src/mini_audit_pro.c, registering ExecutorEnd_hook and ProcessUtility_hook to capture INSERT/UPDATE/DELETE and CREATE/ALTER/DROP TABLE events, enqueueing AuditEvent records into a shared-memory ring buffer protected by a spinlock.
• Add a background worker mini_audit_worker_main that wakes periodically (or via latch), drains up to a batch of events, and writes them to mini_audit_log using SPI inside a transaction with error handling.
• Provide SQL install files sql/mini_audit_pro--1.0.sql and wrapper sql/mini_audit_pro.sql, a README.md documenting architecture and configuration GUCs (mini_audit.enable, mini_audit.tables, mini_audit.queue_size, mini_audit.flush_interval_ms, mini_audit.worker_database), and a test.sql smoke script.

Testing

• No automated CI tests were executed as part of this rollout.
• A manual smoke test script is included at contrib/mini_audit_pro/test.sql which can be run with psql -f contrib/mini_audit_pro/test.sql after installing the extension to verify basic capture of DML/DDL into mini_audit_log.

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Codex Task