[bfrancojr]

Fixes #47, by the option the owner chose there (option 2).

What changes

A row read as cells (DatasetReader.next_or_none, iteration, Result.datasets) now keeps what protowire-go's DatasetRow keeps. Passed to bind_row, it binds as DatasetReader.scan binds it. Before:

• a list or block cell came back as ("unknown", None), and bind_row refused it;
• 1.5p80 came back as ("float", "1.5"), and a BigFloat bound without its precision.

The public Cell type gains two kinds, and the precision suffix stays in the raw text:

("list", [("int", "1"), ("string", "s"), ("list", [("int", "2")])])
("block", [
    ("type", "t/x", None, False),                           # @type = "t/x"
    ("field", "k", ("int", "1"), False),                    # k = 1
    ("block", "m", [("field", "n", ("int", "2"), False)], False),  # m { n = 2 }
    ("map", "q", ("int", "3"), True),                       # "q": 3
])
("float", "1.5p80")

An entry is (kind, key, value, quoted), one kind for each of cpp's entry types (Assignment, MapEntry, Block, TypeEntry). quoted keeps a key written as a string literal, which tells the string map key "1" from the integer key 1. The conversion in module.cc is now recursive in both directions. On the way back the suffix is split off at its p. That's unambiguous, because PXF numbers are decimal: cpp's LexNumber has no hex form, and LexPrecision takes p followed by digits.

Breaking for callers: float(cell[1]) now raises on a suffixed number, where before it silently dropped the precision. This is in the changelog.

Evidence

Built from this branch into a fresh venv (protowire-cpp v2.1.0, CPython 3.15, macOS arm64): pytest tests → 207 passed, the 200 from main plus 7 new in tests/test_pxf_bind_row.py:

• test_a_row_read_as_cells_binds_as_scan_binds_it[list-cell, block-cell, nested-cells, cell-framing]: each row from iteration, bound with bind_row, gives the bytes protowire-go v1.17.0 gives for that fixture (the _ACCEPT table from pxf.bind_row promises (pxf.default) and (pxf.required) but applies neither #24). These are the four fixtures Dataset cells lose list/block values and precision suffixes, so bind_row on them differs from scan #47's done-when names. nested-cells covers map entries and nested blocks.
• test_a_precision_suffix_survives_the_cell: (1.5p80) reads as ("float", "1.5p80"), binds with prec == 80, and gives the same bytes as scan.
• test_list_and_block_cells_keep_their_parts: the shape above, all four entry kinds plus a quoted key and a nested list.
• test_a_list_element_cannot_be_absent: ("list", [None]) is a ValueError.

An unreleased changelog line from #24, "a cell may hold a list or a block (scan only; see #47…)", is updated, since scan is no longer the only way.

[bfrancojr]

CI at 9e34f38: all 18 checks pass (Linux, macOS and Windows on py3.10–3.13, the three cibuildwheel builds, CodeQL).