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

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

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+# BACKLOG — Phase `parse`
+
+## Build backlog
+
+- [x] D1 — Precedence: implement grammar with `*`/`/` tighter than `+`/`-`
+- [x] D2 — Left associativity: iterative left-fold in `_expr` and `_term`
+- [x] D3 — Parentheses: `_primary` handles `LPAREN expr RPAREN`
+- [x] D4 — Unary minus: `_unary` handles leading `-` recursively
+- [x] D5 — Errors: `ParseError` raised for all malformed inputs
+- [x] D6 — Tests green: `calc/test_parser.py` with 23 structural assertions
+
+## Adversary findings
+(none yet)