feat: improve schema guidance and docs

[dlukt]

Summary

• add fuzzy matching suggestions for unknown DSL functions, methods, and field types during schema parsing
• expand parser tests to verify hint generation for field methods, field types, and top-level helpers
• bundle a DSL quick-reference cheat sheet in both the documentation set and erm init scaffold, while refreshing CLI docs with dry-run/force guidance

Testing

• go test ./generator -count=1
• go test ./cli -count=1

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https://chatgpt.com/codex/tasks/task_b_68f18367fae0832e9c5a1cbf24d7f445