* fix(renderer): fit short Cartesian charts (#1968)
ECharts default grid margins consume 145px and collapse short charts. Use relative margins with label containment and a scrollable legend in the app and SDK, leave room above line labels, and preserve explicit imported plot rectangles. Register ECharts 6 containment compatibility and cover real SVG layout, text bounds, and resize behavior.
* fix(renderer): keep compact chart endpoint labels visible
* fix(deps): sync renderer ECharts peer constraint in lockfile
* fix(renderer): size chart text and legend margins in pixels
Percentage text margins over-reserved space on normal-size charts: an 800x450 two-series line plot shrank from the 305px main baseline to 214px. Use 22px label headroom and a 26px legend row, and verify normal-size plot height and resizing in both builders.