feat: implement dynamic distinctipy and colorblind-friendly schemes (#14)

[XinkeLi-UChicago]

Closes #14

Description

This PR implements the requested enhancements for game tree coloring, including a dynamic high-contrast scheme and an accessibility-focused option:

1. Robust limits for the "gambit" scheme: Added a defensive check in get_player_color. If a game exceeds 6 players, it now raises a descriptive ValueError recommending the new dynamic schemes, replacing the silent fallback to black with an explicit error.
2. Dynamic "distinctipy" scheme integration: Introduced a new color scheme using the distinctipy library. It dynamically generates high-contrast, deterministic colors (via a fixed rng seed) for an arbitrary number of players. The chance node color and background colors are explicitly excluded from generation to ensure visual clarity.
3. Accessibility-focused "colorblind" scheme (Bonus): To ensure inclusive visualization, I added a colorblind scheme leveraging distinctipy's built-in Deuteranomaly simulation. This allows game trees to be easily interpreted by individuals with the most common form of color vision deficiency.

Changes

• src/draw_tree/core.py: Modified get_player_color, color_definitions, and generate_tikz to support dynamic player counting and multiple color schemes.
• pyproject.toml: Added distinctipy to the runtime dependencies.

Implementation Notes

• The required number of colors is scanned efficiently from the Game object or the .ef file.
• Edge case considered: For .ef files using inline player definitions, the scanner safely falls back to generating 6 distinct colors to guarantee rendering stability.

How to test

# 1. Existing gambit scheme still works for <= 6 players
draw_tree(g, color_scheme="gambit")

# 2. Error is explicitly raised for >6 player games with gambit scheme
# draw_tree(large_game, color_scheme="gambit")  # raises ValueError

# 3. New distinctipy scheme handles any number of players deterministically
draw_tree(g, color_scheme="distinctipy")

# 4. Colorblind-friendly scheme for accessible visualizations
draw_tree(g, color_scheme="colorblind")

[edwardchalstrey1]

Thanks for this @XinkeLi-UChicago - we've received your email regarding the project proposal and looking into a different project idea - give us a bit of time to respond properly and I will review this PR once we've got that sorted. Thanks!

[XinkeLi-UChicago]

Thanks @edwardchalstrey1! Just a heads-up: the earlier CI failures were due to an edge case with unassigned nodes (player < 0). I've pushed a fix in my latest commit.
Take your time on the Idea 9 or Idea 6 discussion -- happy to wait.