fix: Fix index out of bounds in shanten table when encoding 14-tile hands

[smly]

• Fix a panic (index out of bounds: the len is 15 but the index is 15) in hash_shupai when encode_shanten_efficiency / encode_extended is called during tsumo phase (14-tile hand)
• Add calculate_effective_tiles_auto / calculate_effective_tiles_3p_auto that correctly handle both 13-tile (3n+1) and 14-tile (3n+2) hands

[Copilot]

Pull request overview

Fixes a panic in shanten/efficiency feature encoding when the encoder is invoked during the tsumo phase (14-tile hands), and adds tooling/docs to validate and describe the feature outputs.

Changes:

• Add calculate_effective_tiles_auto / calculate_effective_tiles_3p_auto and route shanten-efficiency encoding through them to avoid 15-tile shanten evaluations.
• Normalize replay Ankan actions’ consumed tiles to a canonical 4-tile set.
• Expand Python stub docstrings with explicit shapes/dtypes and add a Tenhou log validation script.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/riichienv/_riichienv.pyi	Adds detailed docstrings for observation encoders (shapes/dtypes/examples).
scripts/validate_tenhou_logs.py	New end-to-end replay/encoding validator for Tenhou logs (4P/3P).
riichienv-core/src/shanten.rs	Adds auto effective-tile helpers and asserts to prevent invalid hand sizes.
riichienv-core/src/replay/mod.rs	Canonicalizes Ankan consumed tiles in replay step iterator (4P/3P).
riichienv-core/src/observation_3p/python.rs	Switches shanten-efficiency effective-tile calc to the new 3P auto helper.
riichienv-core/src/observation_3p/encode.rs	Switches shanten-efficiency effective-tile calc to the new 3P auto helper.
riichienv-core/src/observation/python.rs	Switches shanten-efficiency effective-tile calc to the new auto helper.
riichienv-core/src/observation/encode.rs	Switches shanten-efficiency effective-tile calc to the new auto helper.

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