Modelly 1.4.1

A patch release: three operations that grew quadratically with the size of a run now grow
linearly, one recorder returns the same rows as the others, and the documentation has a
navigation that fits the screen. Results are unchanged; no core operation is slower than 1.4.0
(python -m modelly.dev perf, the 17 operations paired against the 1.4.0 build).

Performance

• ParquetDataRecorder rewrote its whole file every 1000 rows, so a run's writes were
  quadratic in its rows. The buffer now grows with the file, holds one DataFrame per snapshot
  instead of one dict per row, and summary() reads the row count from the file footer. 2000
  agents recorded for 200 steps take 1.0 s instead of 7.9 s, and twice the steps take twice
  the time (single runs on this machine; the frames are identical to 1.4.0's, dtypes included,
  overwrites and small buffers too).
• Adding or removing a cell of a discrete space visited every cell to reset the empty-cell
  index, even when it had never been built; it now does only when the index exists, which
  detaches the same cells, so random draws are unchanged. Network.remove_cell no longer
  scans its KD-tree list per cell. Removing half of a 32,000-node network takes 0.14 s instead
  of 7.9 s.
• run_batch and run_grid hand each worker a sixteenth of its share at a time instead of one
  task: 20,000 short tasks on eight workers spent 0.49 s in hand-offs, now 0.01 s. Small
  batches still go one task at a time; results and their order are unchanged.

Fixed

• JSONDataRecorder returned a numpy dataset as one row per snapshot holding the nested list
  of values. It now gives one row per agent with agent_id, the fields and time, as the
  memory, Parquet and SQL recorders do, and save_to_json writes those records; a snapshot of
  no agents adds no row.
• Network drops a cell replaced by add_cell at the same coordinate from its KD-tree, so
  find_nearest_cell cannot return it.

Documentation

• Six header sections (Get started, Examples, Guides, Performance, API, Releases) instead of
  six links and a More menu of 29 that ran past the bottom of the window; every page shows its
  section's navigation in the sidebar. No page moved.