v1.10.0

A feature and robustness release: a new terminal heatmap view, a major
upgrade to the Qt6 desktop GUI (vvg), and the remaining high-severity
correctness/OOM fixes from the code audit.

Added

• --heatmap — render the numeric columns as a colour heatmap in the
  terminal (rows × numeric-columns, globally normalised, viridis palette).
  --image-mode selects the backend: auto (kitty graphics if supported, else
  half-block), kitty, sixel, halfblock, or ascii. When stdout is not a
  terminal a plain ASCII intensity grid is written instead of raw escape
  sequences.
• Qt6 GUI (vvg) — a real desktop application: menu bar, File▸Open
  (multi-file → tabs), drag-and-drop, recent files, and error dialogs; a
  genomic region/tabix query bar with a pileup toggle (re-opens BAM/VCF/BED
  over a region); a View menu (column show/hide, go-to-row, shortcuts help).
  Filtering, sorting and find now run off the UI thread with a progress bar
  and a Cancel button, so the window stays responsive on large files.

Fixed

• HDF5 / AnnData — a dense X matrix tab is previewed (first 1000 rows ×
  200 columns) instead of densifying the entire matrix into RAM, which could
  OOM/abort the reader on a real dataset.
• Workbooks (XLSX & ODS) — a row wider than the header no longer makes
  Arrow reject the whole sheet; every row is padded to the widest and the
  overflow header columns are named colN.
• ODS — table:number-rows-repeated on a non-empty row now expands to N
  rows (capped) instead of silently dropping the duplicates.
• TUI — sort / filter / stats / search drain a streaming source to EOF
  first, so they cover the whole file instead of only the chunks scrolled
  through so far.
• --heatmap — Inf/NaN cells no longer poison normalization (they're
  treated as gaps); the scan buffer is bounded; non-TTY output is guarded.
• KDE plugins — the Dolphin thumbnailer and KFileMetaData extractor handle
  malformed input gracefully (empty result, no worker abort).

Performance

• GUI — row→chunk mapping is O(log chunks) via a cumulative-offset binary
  search (was O(chunks) per cell); find navigates a precomputed match list in
  O(log matches) and uses an Arrow match_substring prefilter for literals.

Docs

• Documented --heatmap / --image-mode, NumPy .npz / .npy, and .fods
  across --help, the man page, the README, and the bash/fish/zsh completions;
  clarified that the KF6 GUI plugins are optional.