Release v4.242.0

Added

• Source-events captures can declare key <property> is event source: every captured event is then sourced by the capture's key, a fixture without for takes the key, and a fixture whose source disagrees is rejected. Only a source events capture with a single property key may declare it (PLAY0809). Models that use it select ESM v33; other models keep their version and bytes. (#1042)
• Authoring syntax and diagnostics for clock offsets (today - 7 days, now + 2 hours), date operands (date of occurred), application time zones, command calendars and specification time zones (PLAY0812, PLAY0813, PLAY0814). Executable binding still refuses them with PLAY0268; bare today and now remain ordinary property paths. (part of #824)