lean4-skills-lite

Search Lean 4 libraries (Mathlib, Init, Std, Batteries) for lemmas, theorems, definitions, type classes, notation, and tactics. Invoke BEFORE guessing any Lean/Mathlib name, grep'ing a local mathlib clone, reading mathlib source files, or WebFetch'ing leanprover-community pages. Also invoke when picking premises for simp/aesop/grind, when checking if a lemma exists, or when looking up the canonical name of a known concept. Trigger phrases: 'does mathlib have', 'find lemma', 'what theorem', 'search mathlib', 'is there a lemma for'. Also triggers on loogle query syntax like '?a -> ?b' and on Lean goal text starting with '⊢'. Mathlib is large and naming is non-obvious — assume the lemma exists and search first.