Colour cells by group, shade by member, in both legend-muting modes (#181)

[jepegit]

Closes #181.

Stacked PR (merging is blocked for the agent's token): #189 (#186) → #190 (#184) → #191 (#187) → #192 (#174) → this (#181). Base is cursor/174-open-project-append-713a; retarget to main once #192 lands.

Problem

Turning Mute by group off recoloured the figure. The app colorway (collect._apply_colorway, used by the safe/muted schemes) was keyed by Plotly legendgroup, which cellpy sets to the group id when muting is on but to the cell name when it is off — so every cell got its own colour and the group identity was lost. With muting on, the opposite problem: cells of one group were painted in identical colours and could not be told apart.

Change

• collect.cell_groups(records) maps trace names (batch keys and group names) to group ids; plotting.summary_figure and plotting.cycles_figure (per_cycle layout) pass it to figure_json(cell_groups=…).
• _apply_colorway buckets per-cell traces by group and paints each group with one hue — the scheme colour at (group − 1) % len, so the safe scheme matches the sidebar swatches, or for the cellpy scheme the colour cellpy already gave the group — fanned into lightness shades per member (_shade_series, HLS). Singletons keep the base colour exactly.
• Colours are now identical whether muting is on or off; muting only decides what a legend click toggles.
• Group-average traces and per_cell cycle facets (coloured by cycle) keep the previous order-of-appearance behaviour.
• Colouring runs before legend truncation in _restyle so truncated names cannot collide.
• Also sweeps the solved name of groups #187 issue files out of 01-current-issues (left behind by Name groups: library labels, legend captions, manifest + journal persistence (#187) #191).

Tests

New section in tests/test_core.py: cell_groups map, _shade_series, summary colours follow groups for every scheme × both muting modes, both muting modes give identical colours, Cycles pane follows groups while per_cell stays coloured by cycle, group averages keep their swatch colours. Full suite green locally.

Walkthrough

Demo cells, two cells put in group 1 and one in group 2, Safe scheme: the group-1 cells are two shades of the swatch blue, group 2 is orange; unticking and re-ticking Mute by group leaves the colours unchanged; the Cycles tab follows the same grouping.

issue181_group_colours_muting_walkthrough.mp4

Docs

plot-appearance.md, group-legend-muting.md, README feature line, llms-full.txt regenerated.

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