Use LRU cache for keybinding when-expression AST parsing

- add reusable `LruCache` utility with bounded eviction
- replace keybinding AST cache clear-all behavior with true LRU lookups
- add unit tests for eviction, recency updates, and capacity validation
b81b5616ecJulius Marminge committed on 2/15/2026, 9:25:47 PMparentbe32ce9
3 files changedLine totals unavailable