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

calculators/builder-adversary-lean/run-01/machine-docs/BACKLOG-lex.md

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+# BACKLOG — Phase lex
+
+## Build backlog
+
+- [x] Create calc/ package with __init__.py
+- [x] Implement calc/lexer.py: Token dataclass, LexError, tokenize()
+- [x] Implement calc/test_lexer.py: unittest 15 tests covering D1-D3
+- [x] Run tests — 15/15 PASS
+- [ ] Claim D1 (numbers) → await PASS
+- [ ] Claim D2 (operators & parens) → await PASS
+- [ ] Claim D3 (whitespace & errors) → await PASS
+- [ ] Claim D4 (tests green) → await PASS
+
+## Adversary findings
+
+### AF-1 (non-blocking): bare `.` leaks `ValueError` instead of `LexError`
+- Repro: `tokenize('.')` → `ValueError: could not convert string to float: '.'`
+- Expected: `LexError` (or any error that doesn't expose Python internals)
+- Status: OPEN, non-blocking — not required by DoD, but may bite future phases