fix: identify the SQLx adapter crate as part of Casbin

[EmryZhang]

The 1.9.0 RC1 review asks for a crate name that identifies Casbin. This change proposes casbin-sqlx-adapter, updates the registry/docs links, installation examples, release notes and release-script fixture, and corrects the SQLx display spelling.

An explicit [lib] name = "sqlx_adapter" preserves Rust imports and the SqlxAdapter public type. The README explains the dependency-name migration and when the new registry links become available. Production code, feature support, dependency versions and ASF source-archive naming are unchanged.

Validation:

• The 26-file source preview and newly built 20-file crate were checked against recorded hashes. Source files and LICENSE/NOTICE/DISCLAIMER match; the packaged manifest uses the proposed package name and retains the library name.
• The project-configured RAT 0.16.1 scan reports 21 approved text files, three legal documents and the two documented policy-CSV exclusions. Complete ASF headers and supplemental Rust/shell coverage were separately reviewed.
• With Rust 1.94.0 on Windows GNU: formatting, default build, Clippy with warnings denied, and cargo package --locked --allow-dirty including package verification pass. A separate consumer compiles against the extracted crate using sqlx_adapter::SqlxAdapter.
• All 12 combinations of SQLite/MySQL/PostgreSQL and the four supported runtime/TLS features pass, with three tests each (36 test executions). MySQL 8.0.44 and PostgreSQL 17.11 ran as disposable native instances; no Docker was required.
• Workflow linting, shell syntax and offline release-script checks passed for the same patch inputs. CI must validate the submitted revision before merge.

The proposed registry name returned 404 when checked; that does not reserve it or establish project ownership. Confirm the name and project publishing administration before the new release. No registry package or new release candidate is published by this change.