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

calculators/builder-solo/run-04/machine-docs/JOURNAL-lex.md

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+# JOURNAL-lex
+
+## 2026-06-15
+
+**Built:** `calc/__init__.py`, `calc/lexer.py`, `calc/test_lexer.py`, `.gitignore`
+
+**Design decisions:**
+- `Token` is a `@dataclass` with `kind: str` and `value: Union[int, float, str, None]`
+- Operators/parens carry their char as value; EOF carries `None`
+- Number parsing: scans contiguous digits/dots; if `.` present → `float()`, else `int()`
+- `LexError` extends `Exception`; message includes repr of bad char and its index
+
+**Verification (all 3 plan commands passed):**
+1. `python -m unittest -q` → 15 tests, 0 failures
+2. `tokenize('3.5*(1-2)')` → correct 8-token list
+3. `tokenize('1 @ 2')` → raises `LexError: unexpected character '@' at position 2`
+
+**Commit:** c37b70f — pushed to origin/main