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

calculators/builder-adversary-lean/run-04/machine-docs/BACKLOG-lex.md

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+# BACKLOG — phase lex
+
+## Build backlog
+
+- [x] Create calc/ package (calc/__init__.py)
+- [x] Implement calc/lexer.py (Token, LexError, tokenize)
+- [x] Implement calc/test_lexer.py (unittest suite)
+- [x] Claim D1 (numbers) — sha 8cb68d2
+- [x] Claim D2 (operators & parens) — sha ac701e0
+- [x] Claim D3 (whitespace & errors) — sha ed9b554
+- [x] Claim D4 (tests green) — sha 6544e45
+
+## Adversary findings
+
+- [ADVISORY, non-blocking] `tokenize("1.2.3")` raises bare `ValueError` instead of
+  `LexError`. Greedy dot-consuming loop accumulates "1.2.3", then `float()` crashes.
+  Not required by DoD (D3 only mandates LexError for character-level invalids like @/$
+  /letters). Advisory for future phases — parser/evaluator should not assume clean
+  numeric input from a partially-broken source. (Found 2026-06-15T05:54:37Z)