[tonyalaribe]

Commands issued inside an aborted explicit transaction currently return SQLSTATE 25P01 (no active transaction). Return PostgreSQL's 25P02 (in failed transaction) from both the ordinary-query and BEGIN rejection paths. Commands remain refused until rollback.

Strengthen the existing transaction integration test to require exact 25P02 for SELECT 1 and BEGIN, then verify rollback recovery.

Validation:

• The strengthened Python test fails on the currently pinned consumer with 25P01 and passes against this corrected source through a real local TimeFusion server.
• A consumer Rust wire test fails before the change, then passes all four simple/extended × query/BEGIN cases, including exact SQLSTATE and rollback recovery.
• All 10 selected consumer PGWire regression tests pass with retries disabled; consumer cargo lint passes.
• Fork cargo fmt --all -- --check, Python syntax, and diff checks pass.

The fork base tree matches consumer pin 1388ea37 exactly. Consumer verification uses a local path to this fork. All 14 standalone fork CI jobs pass, including the three integration variants and clean Linux build. Final immutable consumer-pin validation is running separately.