Added Dynamic Search Rules API support to the official Java client, implementing list, get, create/update, and delete operations with integration tests.

Standardized null-body validation across 14 REST endpoints so requests with empty bodies return HTTP 400 instead of HTTP 500, adding 14 tests and lifting server coverage from 81.95% to 88.49%.

Added structured GitHub issue forms (bug report, feature proposal) and a PR template to standardize contributions.