0.9.0

Screen-reader pairings tested: none yet (issue #5).
Browsers: Chromium (the whole e2e suite, 1053 passed) and WebKit (Playwright's, not Safari:
519 passed, 10 skipped). Firefox: not run.

The pivot grows: two column dimensions with a named header, and limits set by a measurement of
what a browser draws as a table in about a second.

What breaks:

• A pivot over the new budget of 131 072 cells is an error now, though its rows and columns are
  each inside their limits — 2 000 rows × 256 columns was allowed before (E39).
• Rust: PivotLimits has a new field, max_cells.

Module sizes (brotli, just measure-modules): the elements 224.0 → 224.8 KiB, the engine
118.8 KiB, both inside their bounds.

Fixed

• An answer no longer takes the focus away in <opengrid-pivot> (#124).
  Every answer redraws the pivot; a reader on a toolbar control, a sort or fold button, or
  typing into the filter field lost the focus and the typed text. The focused control is found
  again after a redraw, and the field keeps its text — until the expression is added.

Changed

• The pivot's limits follow a measurement (#122, E39).
  A browser draws a native table in time proportional to its cells, whatever their shape
  (just measure-pivot: 128 000 cells in 0.7 s in Chromium, 1.0 s in WebKit; 512 000 in 3.1 s
  and 4.7 s). So a pivot now has a budget of 131 072 cells (rows × generated columns,
  PivotLimits::max_cells, reported by GET /source), the row limit rises from 2 000 to
  10 000 and the column limit stays 256. What breaks: a pivot wider than the budget —
  2 000 rows × 256 columns was allowed — is an error with a sentence now. Rust: PivotLimits has
  a new field.

Added

• Two column dimensions in <opengrid-pivot> (#120).
  columns="ordered_year,status" gives a header row per dimension, the outer value spanning its
  inner ones, then the measures. With two, the pivot is a complex table: every header cell has an
  id and every value cell headers naming its row and column headers. The engine's limit
  (PivotLimits::max_column_dimensions, reported by GET /source) is 2 now; three is an error
  with a sentence. The toolbar offers "+ Column" until there are two; columnFull reads "Two
  column fields already". Conformance cases with two column dimensions run on every path.