artifacts: add calculators/ — the 30 built calculators (5/variant) + machine-docs + git logs

calculators/builder-adversary-stateless/run-03/machine-docs/BACKLOG-lex.md

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+# BACKLOG — Phase `lex`
+
+## Build backlog
+
+- [x] D1: integers and floats tokenize correctly
+- [x] D2: operators and parens tokenize correctly
+- [x] D3: whitespace skipped; invalid chars raise LexError
+- [x] D4: test suite green (21 tests, 0 failures)
+- [ ] Await Adversary PASS on D1–D4
+
+## Adversary findings
+<!-- Adversary writes here -->