fix(3p): correct dead wall layout and rinshan draw logic (#183)

[smly]

Fix a bug where dora indicator tiles could be consumed by rinshan draws in 3P mode, causing a tile type to appear more than 4 times (#183). Plus,

• Refactor both 3P and 4P to use a drawable_count counter instead of comparing tiles.len() against a magic number
• Fix an off-by-one in replay initialization that made the last kita/riichi incorrectly illegal

Root cause

In 3P mahjong, both kan and kita (north extraction) draw rinshan tiles from the dead wall. The old implementation allocated only 4 rinshan slots (same as 4P), but 3P requires 8 (4 kan + 4 kita). After the 4th rinshan draw, tiles.remove(0) consumed dora indicator tiles, making them appear both on the dead wall and in a player's hand.

Validation

• MjSoul 3P paishan validation: 1,814 kyoku, 60,387 draws (55,517 normal + 4,870 rinshan), 0 failures
• validate_logs.py 3P: 5000/5000 passed
• validate_logs.py 4P: 5000/5000 passed

Closes #183

[Copilot]

Pull request overview

Fixes a 3P (sanma) wall-layout bug where rinshan draws could consume dora indicator tiles (leading to an indicator tile type appearing “5 times”), and refactors wall exhaustion logic in both 3P and 4P to use an explicit drawable_count rather than tiles.len() magic-number checks.

Changes:

• 3P: Adjust wall layout / rinshan draw path to prevent consuming dora/ura indicator tiles; add regression tests in WallState3P.
• 3P + 4P: Introduce and plumb drawable_count through draw/exhaustion/riichi/haitei/houtei logic and replay event handling.
• Tests + replay init: Update unit tests and replay initialization to keep drawable_count in sync (fixing the reported off-by-one legality issue).

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
riichienv-core/src/state_3p/wall.rs	Reworks 3P indicator indexing and adds draw_rinshan_tile() plus regression tests for issue #183.
riichienv-core/src/state_3p/sanma.rs	Switches kita legality and rinshan draw to use drawable_count and draw_rinshan_tile().
riichienv-core/src/state_3p/mod.rs	Updates 3P riichi/haitei/houtei/kan draw/deal flow to use drawable_count; initializes the counter per-round.
riichienv-core/src/state_3p/legal_actions.rs	Aligns 3P legal-action gates (riichi/kan/haitei/houtei/pon/kan) with drawable_count.
riichienv-core/src/state_3p/event_handler.rs	Keeps replay-driven wall consumption consistent by decrementing drawable_count when popping wall tiles.
riichienv-core/src/state/wall.rs	Adds drawable_count to the 4P wall state and resets it on shuffle/load.
riichienv-core/src/state/mod.rs	Refactors 4P riichi/haitei/houtei/kan draw/deal flow to use drawable_count; initializes the counter per-round.
riichienv-core/src/state/legal_actions.rs	Aligns 4P legal-action gates (riichi/kan/chi/haitei/houtei/pon/kan) with drawable_count.
riichienv-core/src/state/event_handler.rs	Keeps replay-driven wall consumption consistent by decrementing drawable_count when popping wall tiles.
riichienv-core/src/replay/mod.rs	Fixes replay initialization accounting by incrementing drawable_count when pushing back the oya draw tile.
riichienv-core/src/replay/mjai_replay.rs	Updates documentation comment to match the “non-drawable reserve” concept.
riichienv-core/src/tests.rs	Updates sanma unit tests to set drawable_count after overriding the wall tiles.

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