parser

type Document struct {
	Filename    string
	TotalTokens int
	Sections    []*Section
	References  []Reference // Links to other .md files
}

type Reference struct {
	Text   string // Link text
	Target string // Target file path
	Line   int    // Line number where reference appears
}

type Section struct {
	Level     int // 1 = #, 2 = ##, etc.
	Title     string
	Content   string   // raw content (excluding children)
	Tokens    int      // estimated tokens for this section
	KeyTerms  []string // extracted key concepts
	Children  []*Section
	Parent    *Section
	LineStart int
	LineEnd   int
}