数式変換候補を追加 / Add formula conversion candidates

[KazumaProject]

日本語

概要

数式の簡易記法と限定的なLaTeX記法を解析し、Unicode表示と正規化LaTeXを変換候補として提示します。

• Androidに依存しない数式AST／パーサー／レイアウトエンジンを追加
• 分数、累乗・添字、根号、総和・積分、区切り記号、ギリシャ文字などを候補化
• 候補のcommit textとCanvas表示を分離し、候補順序・全角候補との位置関係を整理
• 設定、候補表示、README、ユニットテストを追加

依存関係

codex/feature/inline-suggestion-toggle を先にマージしてください。このPRのベースも同ブランチです。

確認

• FormulaParser / FormulaLayout / UtilityCandidateProvider / UtilityCandidateComposer の対象テスト pass
• git diff --check pass
• 実機で候補表示・commit text・Canvas描画の確認推奨

English

Summary

Adds formula conversion candidates by parsing a conservative shorthand and a finite LaTeX subset, exposing Unicode and normalized LaTeX candidates.

• Adds an Android-independent AST, parser, and layout engine
• Covers fractions, scripts, radicals, large operators, delimiters, and Greek symbols
• Separates committed text from Canvas presentation and orders formula candidates with existing/full-width candidates
• Adds settings, candidate rendering, README documentation, and unit tests

Dependency

Merge codex/feature/inline-suggestion-toggle first; this PR uses that branch as its base.

Verification

• Targeted FormulaParser / FormulaLayout / UtilityCandidateProvider / UtilityCandidateComposer tests pass
• git diff --check passes
• Device verification is recommended for candidate commit text and Canvas rendering