feat(markdown): add treeblood extensions for enhanced markdown parsing

[yoonhyunwoo]

마크다운 수식 랜더링 익스텐션 추가

[Copilot]

Pull Request Overview

Adds a math rendering (MathML) extension to the Goldmark markdown pipeline to enable formula parsing/rendering. Also introduces new markdown-related dependencies to go.mod.

• Add goldmark-treeblood MathML extension into markdown renderer setup
• Add new dependencies (goldmark-treeblood and treeblood) to go.mod

Reviewed Changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated 2 comments.

File	Description
internal/markdown/parse.go	Imports and registers treeblood MathML extension in the Goldmark configuration
go.mod	Adds goldmark-treeblood and treeblood modules as (currently marked) indirect dependencies

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[Copilot]

The module github.com/wyatt915/goldmark-treeblood is directly imported in internal/markdown/parse.go, so it should not be marked as // indirect. Remove the comment and run go mod tidy to reflect it as a direct dependency.

Suggested change

	github.com/wyatt915/goldmark-treeblood v0.0.0-20250825231212-5dcbdb2f4b57 // indirect
	github.com/wyatt915/goldmark-treeblood v0.0.0-20250825231212-5dcbdb2f4b57

[Copilot]

Adding a new rendering capability (MathML) changes supported markdown features; consider adding a brief comment here (or updating higher-level markdown/rendering docs) to explain why MathML is enabled and any implications (e.g., output format expectations or security considerations if user-supplied content is rendered).

Suggested change

	),
	),
	// Enable MathML rendering for mathematical expressions in markdown.
	// MathML output allows rich math formatting, but note:
	// - Output will include <math> elements, which may not be supported by all HTML consumers.
	// - If user-supplied content is rendered, ensure proper sanitization to prevent XSS or other security issues.
	// - See higher-level markdown/rendering docs for more details.