GeezerVison

Add structured parsing for PostgreSQL/MySQL transaction starts, completion chaining and savepoint release. StartTransaction exposes the command and ordered typed modes; Commit/RollbackStatement share keyword and chain enums while retaining existing rollback APIs; ReleaseSavepointStatement preserves the name and optional SAVEPOINT keyword. Connect rendering, visitors, transaction-effect analysis, table finding and feature validators, with PostgreSQL chaining gated to version 12+.

Explicit PostgreSQL/MySQL dialects disambiguate transaction BEGIN from procedural blocks. Default BEGIN keeps its existing block behavior. PostgreSQL accepts optional commas between modes; MySQL enforces its characteristic restrictions and rejects contradictory READ ONLY/READ WRITE modes while allowing repetitions. Documentation covers that policy. MySQL completion [NO] RELEASE, XA, prepared transactions and SET TRANSACTION remain outside this PR.

Validation:

• Full Java 17 Gradle check: 9,041 tests, zero failures/errors, 25 skipped; 77 dedicated transaction tests and zero grammar choice conflicts; formatting/static analysis passed.
• PostgreSQL 18.6 and MySQL 9.7.2/26.7.0: 165 original/toString()/deparser executions with matching activity, modes, read-only enforcement, snapshot visibility, committed rows, CHAIN behavior and savepoint state.
• Regression coverage includes quoted savepoints, mutable ASTs, direct/Reader/utility entry points, statement boundaries, visitors, capability validation, malformed/deferred syntax, procedural-block compatibility and RELEASE identifier usage.
• An unchanged client and concrete StatementVisitor compiled against the base ran on the new runtime, including legacy rollback APIs and the new default visitor methods.
• Existing JMH corpus and configured-script smoke checks used two forks with allocation profiling; existing-corpus allocation remained approximately 7.77 MB/op. Short timing samples are not a speed claim.

References: PostgreSQL START TRANSACTION, PostgreSQL COMMIT, MySQL transaction control.