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

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

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+# BACKLOG-eval
+
+## Build backlog
+
+- [x] D1 arithmetic — `evaluate()` correct for +/-/*//, precedence, parens, unary minus
+- [x] D2 division — true division; `EvalError` on zero; not bare `ZeroDivisionError`
+- [x] D3 result type — whole floats → int; non-whole → float; rule documented in evaluator.py
+- [x] D4 CLI — `calc.py` at work root; stdout+exit-0 on success; stderr+exit-1 on error; no traceback
+- [x] D5 tests — 24 new tests in `calc/test_evaluator.py`; 68 total pass; prior suite unaffected
+
+## Adversary findings
+_(none yet)_