Bump github.com/NimbleMarkets/ntcharts/v2 from 2.4.0 to 2.6.0

[dependabot]

Bumps github.com/NimbleMarkets/ntcharts/v2 from 2.4.0 to 2.6.0.

Changelog

Sourced from github.com/NimbleMarkets/ntcharts/v2's changelog.

v2.6.0 (2026-10-01)

• fix(spec): Numeric-X line charts now join each series' points with braille lines instead of drawing baseline spikes. Linear/log scales, series colours, and Y pins are preserved; singleton points draw as dots. Behavior/API change from v2.5.0: Build for ChartTypeLine returns *linechart.Model instead of *wavelinechart.Model. Points are connected in input order, with no connection between series.
• feat(linechart): Add logarithmic axes. linechart.Scale is ScaleLinear (the default) or ScaleLog (base 10), set with WithXScale / WithYScale or SetXScale / SetYScale and read with XScale / YScale; wavelinechart exposes both options, timeserieslinechart and streamlinechart expose WithYScale. Ranges, data points, and label formatter values stay in data units. A log axis labels powers of ten on the rows and columns where they fall (adding 2× and 5× when a range holds fewer than three, and falling back to even spacing in a range too narrow for two round values), with the axis steps as the minimum label spacing. Points at or below zero are not drawn and are ignored by auto-ranging, non-positive range bounds are replaced (minimum = maximum/10, or 1..10), and zoom and pan steps are measured in decades. On a log Y axis a wavelinechart rests on the bottom of the view range. Linear axes are unchanged.
• feat(heatmap): Heatmaps can draw filled cells and name their rows and columns. WithCellSize draws each point as a block that tiles the plot instead of a single character, and WithXLabels / WithYLabels (or SetXLabels / SetYLabels) draw column names under the plot and row names, centred on their rows, in a margin to its left. Existing heatmaps are unchanged unless they opt in.
• feat(examples): Add heatmap/labels, a day-by-time heatmap with filled cells and row and column names, with keys to toggle the labels and resize the chart. It is in the WASM gallery as "Heatmap (labels)".
• feat(spec): Heatmaps are now drawn as filled blocks with their x_axis.labels and y_axis.labels; previously each cell was one isolated character and the labels were ignored. Behavior change: row 0 (and y_axis.labels[0]) is now the top row, as in flint heatmaps, where it used to be the bottom; heatmaps with no labels fill the whole chart; a negative cell index is a Build error.
• feat(spec): Add a logarithmic axis scale. XAxis.Scale / YAxis.Scale accept "linear" (spec.ScaleLinear, the default when empty) or "log" (spec.ScaleLog, base 10); Validate rejects other values. Build honours a log Y axis for line, scatter, timeseries, and OHLC charts and a log X axis for line and scatter, using the chart models' own log scale. Unpinned bounds widen to whole decades, YAxis.Min / Max stay in data units with the same one-sided pin rule, and Format applies as on a linear axis (with a short k/M default when unset). It is a Build error to ask for a log axis on bar, heatmap, or sparkline charts or on a time X axis, or to put a value or pin <= 0 on one. echarts.ToECharts ignores scale for now. See "Logarithmic axes" in spec/README.md.
• feat(examples): Add linechart/logscale, a time series on a log Y axis with a key to toggle linear/log and zoom the Y axis. It is in the WASM gallery as "Log Scale".

v2.5.0 (2026-09-30)

• fix(wasm-build): build TinyGo demos with -gc=boehm, fixing the slow "GPU Shaders (TinyGo)" gallery demo.
• feat(spec): Add spec package for surface-agnostic chart specifications: a JSON-marshalable spec.Spec (type, axes, format directives, series, heat data, OHLC points, options, theme) that spec.Build renders to a bar, line, timeseries, scatter, heatmap, sparkline, or candlestick (OHLC) model. Validate catches structural mistakes up front. See spec/README.md for the schema and the per-surface fidelity matrix.
  • The web surface lives in its own nested module, github.com/NimbleMarkets/ntcharts/spec/echarts/v2 (echarts.ToECharts(s)), published with the spec/echarts/v2.X.Y tag, so the go-echarts dependency stays out of the core library. spec.PointX, spec.PointTime, and spec.DeriveBarLabels are exported for surfaces to share.
  • Bar charts forward y_axis.min to barchart.WithMinValue (negative bars extend the floor automatically); Validate also rejects an unknown x_axis.type or series.type.
  • Terminal builders preserve one-sided Y pins, widen singleton time ranges, and reject insufficient plot space and equal explicit Y bounds. Shared Data.XAxisData supplies omitted X values for bar, line, scatter, and timeseries charts; DeriveBarLabels accepts spec.Data. Heatmap colour-domain pins work independently, and dense matrices map Matrix[y][x] to the same cells as sparse data. OHLC requires exactly one series. ECharts bar charts honour the theme palette.
• feat(timeserieslinechart): DrawCandleWithOpts draws OHLC candles with multi-column bodies, edge insets (so candles at the axis or chart edge shift inward instead of losing part of their body), and a choice of line-rune or solid block bodies through DrawCandleOpts.Block. New graph.DrawCandlestickBottomToTopWide and graph.DrawCandlestickBlockBottomToTop primitives and the runes.UpperHalfBlock constant back them. Candles outside the time viewport remain clipped. Behavior change: DrawCandle now includes candles exactly at the viewport's maximum timestamp.
• fix(linechart): the final X tick uses the true axis maximum. When its label does not fit left-anchored, it is right-aligned if the entire span and its left neighbour are free. Labels that cannot fit, collide, or repeat the preceding label remain hidden. Behavior change: final labels may change value or visibility; existing demo captures may differ.
• fix(picture): query the terminal for Kitty shared-memory (t=s) support at startup, and send direct frames unless it answers OK. Frames were silently dropped on remote hosts and in terminals that cannot read the objects.
• feat(shaders): time each stage of a frame. The header gains a line dividing R into setup / submit / map / copy, and -report adds per-stage summaries (mean, median, 95th percentile over the last 600 frames), startup times, heap size, and the compiler. Existing report fields are unchanged. The browser build publishes the same report in globalThis.ntchartsShadersReport.
• feat(shaders): add -medium shm|direct, and read flags from the page's query string in the browser (?preset=julia&medium=direct).

Commits

• 4467dfb chore(release): v2.6.0
• d515379 fix(spec): render numeric line charts as connected braille lines
• ee1e8ca fix(timeserieslinechart): preserve isolated points on log axes
• 7f6a90d fix(heatmap): clip offscreen cells and fit row labels
• 7da07b2 docs(examples): package the labelled heatmap example
• 26ba48a feat(examples): add a labelled heatmap example
• 5ac1a7a feat(spec): draw heatmaps as filled, labelled grids
• a5bfc30 feat(heatmap): draw filled cells and label rows and columns
• 29e855a feat(examples): add a log-scale time series example
• d177fd3 build: pin the nested modules at the v2.6.0 candidate
• Additional commits viewable in compare view

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[dependabot]

Superseded by #2.