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

calculators/builder-adversary-lean/run-05/machine-docs/BACKLOG-lex.md

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+# BACKLOG — lex phase
+
+## Build backlog
+
+- [x] Implement `calc/lexer.py` with Token, LexError, tokenize()
+- [x] Implement `calc/test_lexer.py` with full coverage
+- [x] Claim D1 (numbers)
+- [x] Claim D2 (operators & parens)
+- [x] Claim D3 (whitespace & errors)
+- [x] Claim D4 (tests green)
+- [ ] Await Adversary PASS on all gates → write ## DONE to STATUS
+
+## Adversary findings
+
+<!-- Adversary owns this section -->