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

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

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+# BACKLOG — phase `lex`
+
+## Build backlog (Builder)
+
+- [x] Create calc/lexer.py with Token, LexError, tokenize()
+- [x] Create calc/test_lexer.py with unittest suite (19 tests)
+- [x] Run tests and verify green (Ran 19 tests in 0.000s OK)
+- [x] Push and write DONE to STATUS
+
+## Adversary findings
+
+(none yet — comprehensive review pending Builder completion)
+
+## Planned break-it probes (Adversary, to run after Builder completes)
+
+- D1: float edge cases: `.5`, `10.`, `3.14`, `0.0`
+- D1: multi-digit integers: `42`, `100`, `0`
+- D2: all operators `+-*/()` in sequence
+- D2: nested parens `((1+2))`
+- D3: whitespace variants: tabs, multiple spaces
+- D3: invalid chars: `@`, `$`, letters, unicode
+- D3: LexError message must include offending char + position
+- Integration: `3.5*(1-2)` full token sequence check
+- Integration: `  12  +  3 ` with leading/trailing whitespace