Class property expressions, class-body arrays, SYS(2007), SET switch words

[jefflroberts]

Found running a CodeMine application (Shutter Ace); each behaviour measured in
Visual FoxPro 9 first, with goldens whose .expected vfp9.exe wrote.

• A DEFINE CLASS property value that is an expression - QuickBooksInvoice's
  TxnDate = TRANSFORM(DTOS(DATE()), "@r xxxx-xx-xx") - is kept as source and
  worked out at CREATEOBJECT(), where CREATEOBJECT() was called, so a variable
  set just before it is seen. A subclass's constant still wins over it. It was
  a compile error. Evaluating in a fiber that is waiting on the host no longer
  drops the answer that fiber is waiting for.
• A class body can set an array property whole (every element) or one element
  of it: DIMENSION wbaSearchOrder[7] then wbaSearchOrder[1] = "WIZARDS",
  as Microsoft's own wbmain.prg does.
• SYS(2007): CRC-16/CCITT from 0xFFFF or from the seed given, and CRC-32 with
  flag 1. CodeMine validates serial numbers with it.
• Words after a SET switch are read: SET COMPATIBLE ... PROMPT | NOPROMPT is
  what SET("COMPATIBLE", 1) answers; the words after others change nothing.

Verification. Goldens class_array_elements, sys_checksum and set_switch_words (each .expected written by vfp9.exe), tests/runtime/classPropertyExpressions.test.ts, and an updated case in crates/foxvm/tests/classes.rs. The full VM suite and the runtime, shared, vfp and reference TypeScript tests pass on this branch.

One of several pull requests split out of work on a CodeMine application (Shutter Ace); each stands on main on its own except where it says otherwise.

🤖 Generated with Claude Code

[RandomChirp]

Measured in vfp9.exe: a class property written as an expression is worked out when the object is made, in the caller's scope (nBase = 7 just before CREATEOBJECT gives nFromVar 8), a subclass constant wins over the parent's expression (cchild.nSum 20), and DATE() there is a date. The three goldens (class_array_elements, set_switch_words, sys_checksum) agree with the product, and cargo test -p foxvm is green on a merge with main.

One small thing, not blocking: SYS(2007) takes the low byte of each char, which folds any character above 255 into a byte the product would never see. The strings the VM holds are single-byte in practice, so it is fine today; a comment saying so would stop someone reading it as a bug.

Review generated with Claude Code (Claude Fable 5.1), run against vfp9.exe and the test suites on a merge with main.