feat: granular label/action styling, GUI settings persistence, and undo/redo (v0.11.0)

[edwardchalstrey1]

Overview

This PR adds per-player/per-level control over label backgrounds and action label positioning, a new gui_settings.yaml persistence layer that auto-saves and restores per-game settings, a multi-step undo/redo system, a Settings download button, and a suite of GUI improvements including a dynamic colour-scheme palette and a colorblind-accessible default.

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API & Core (core.py, cli.py)

Label backgrounds — label_bg now accepts bool | dict[int, bool], enabling selective application per player or per level:

• label_bg_by="player"|"level" — how to interpret a dict key
• label_bg_style="player_bg"|"white_bg" — player-colour background with white text, or vice versa
• CLI: --label-bg=1,2, --label-bg-by=player, --label-bg-style=white_bg
• New helpers _any_label_bg(), _label_bg_active(player, level) used internally

Action label positioning — action_label_position now accepts float | dict[int, float] for per-player or per-level control:

• action_label_position_by="player"|"level" — dict key interpretation
• vary_action_label_positions=True — automatically distributes labels evenly across sibling edges
• vary_action_label_positions_by, vary_action_label_positions_choices for selective application
• CLI: --action-label-position=0:0.3,1:0.7, --vary-action-label-positions, etc.

New public function — get_game_levels(game_source, level_scaling, sublevel_scaling) returns the sorted list of actual level values present in the tree (not just the max), with correct scaling for pygambit games. Exported from draw_tree.

All generate_*, draw_tree, and ef_to_tex signatures updated; commandline() return tuple extended accordingly.

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GUI (app.py)

Settings download — "Settings" button in the Downloads expander writes the current GUI configuration as a YAML snippet ready to paste into the overrides: section of gui_settings.yaml.

Color scheme palette — Default changed from "custom" to "colorblind". The Palette section now appears for every non-"default" scheme, pre-filled with that scheme's actual colours. Editing any colour auto-switches to "custom"; switching back to a named scheme resets the palette to its defaults.

Per-game settings persistence — A new gui_settings.yaml file (committed, not gitignored) stores defaults and per-game overrides. Settings are auto-saved on every change (only values that differ from draw_tree defaults are stored). When the user switches to a game, its saved settings are automatically restored.

Undo / Redo / Reset — Three sidebar buttons with a bounded 50-step undo stack. ↩ Undo / ↪ Redo do full widget-state snapshot swaps; ↺ Reset removes the current game's overrides from gui_settings.yaml and reloads the effective defaults.

Label styling UI — "Enable Label Background" expands into a scope selector (All / By Player / By Level) with multi-select for selective application, a style toggle (player-colour vs white background), and an opacity slider.

Action label positioning UI — Positioning Mode (Global / By Player / By Level) provides per-player or per-level sliders. "Vary Action Label Positions" checkbox with "Vary by" sub-selector applies automatic even spacing, disabling the manual position controls.

Level-based selection fixes — get_game_levels (with correct level_scaling) replaces count_levels for populating level multiselects and sliders, ensuring only levels that actually exist in the tree are shown and that selections take effect correctly.

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Tests & Docs

• TestLabelBackground extended with 9 new cases covering dict label_bg, label_bg_style, and CLI parsing
• All existing commandline() tuple unpacks updated for the two new return values (label_bg_by, label_bg_style)
• docs/python_api.md and docs/cli.md updated with all new parameters

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Dependencies & version

• pyyaml added to dependencies
• Version bumped 0.10.0 → 0.11.0