DRY comptime helpers

[jburgy]

Consolidate defword_, defcode_, defcode, defconst, and defword into just defword with shorter helpers to generate repetitive code such as constants and stack manipulations.

[Copilot]

Pull request overview

This PR consolidates the compile-time helper functions for defining Forth words, reducing code duplication by eliminating defword_, defcode_, defcode, and defconst in favor of a single defword function with specialized helper functions (wrap, attr, value, words) that generate instruction sequences.

Key changes:

• Unified word definition through a single defword function with helper functions for common patterns
• Replaced defcode with wrap() for stack manipulation operations
• Replaced defconst with value() for literal constants and attr() for interpreter field addresses
• Added words() helper to build composite words from other word references

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