api: CompiledRegex should carry its MatchMode to prevent silent misuse

Problem

CompiledRegex stores only nfa : GlushkovNfa with no record of the MatchMode used during compilation. Both matchCompiled and searchCompiled call the identical Glushkov.matchString underneath — the mode distinction is only enforced inside desugar (which wraps unanchored patterns with .* in search mode).

This means a caller who compiles with .search and then calls matchCompiled instead of searchCompiled silently gets wrong semantics — no error, no warning.

-- Silent misuse: compiled for search, used as fullMatch
let compiled ← compile pattern .search
let result := matchCompiled compiled input  -- wrong! should be searchCompiled

Proposed fix

Add a mode : MatchMode field to CompiledRegex and assert (or dispatch) on it in matchCompiled/searchCompiled:

structure CompiledRegex where
  nfa  : Glushkov.GlushkovNfa
  mode : MatchMode
deriving Repr

Option A: panic/error if wrong function called for mode.
Option B: merge into a single runCompiled that dispatches based on stored mode.
Option C: remove matchCompiled/searchCompiled and expose only runCompiled.

Option C (single entry point) is cleanest — callers can't pick the wrong function.

Impact

Breaking API change for matchCompiled/searchCompiled. The CLI (LckGrep.lean) and tests need updating.

まず CompiledRegex、compile、matchCompiled、searchCompiled、desugar を見つけ、次に LckGrep.lean の CLI エントリポイントと影響を受けるテストを調べます。提案されている API の形のうち、どれが意図されたものかを判断し、呼び出し元とテストを更新して、互換性のないマッチモードが暗黙的に使用できなくなっていることを確認します。