refactor(env): materialize grasp caches on cold path

[TATP-233]

Summary

• materialize Allegro rotation grasp caches during env initialization
• resolve and preload Sharpa rotation scale caches during env initialization
• keep reset providers memory-only while preserving grasp-generation owners through an explicit class hook
• preserve explicit default rotation-provider construction and add regression coverage through repeated reset-plan execution

Scope

• Parent umbrella: Work: 代码清理审计 umbrella：边界契约/结构契约/死代码/重复实现/腐化代码结论汇总(只审计) #983
• Resolves child issue Refactor: 将 in-hand grasp cache 解析与加载移出 reset 热路径 #994 after this PR is merged into dev/issue-983-code-cleanup
• Integration target: dev/issue-983-code-cleanup only; no change targets main

Validation

• focused env tests: 73 passed, 3 skipped, 5 deselected
• PYTHONPATH="$PWD/src" UV_NO_SYNC=1 make test-all
• pytest: 1679 passed, 27 skipped, 273 deselected, 1 xfailed
• benchmark smoke: 33/34 module imports and 34/35 script imports; only platform-optional MLX skipped
• Ruff, mypy, and pyright passed
• exact validated head: 4c80e373f6b3bf6416ff0b9fefaee8170a36f4f9