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

calculators/builder-adversary-stateless/run-02/machine-docs/BACKLOG-lex.md

@@ -0,0 +1,12 @@
+# BACKLOG — Phase `lex`
+
+## Build backlog
+
+- [x] D1 — Implement integer/float tokenization → NUMBER tokens
+- [x] D2 — Implement operator/paren tokenization
+- [x] D3 — Whitespace skipping + LexError for invalid chars
+- [x] D4 — Write and pass unittest suite (14 tests, 0 failures)
+- [ ] Await Adversary PASS on D1–D4
+
+## Adversary findings
+<!-- Adversary writes here -->