feat: add README parser with entry extraction and section tree building

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

internal/parser/types.go

@@ -0,0 +1,35 @@
+package parser
+
+// Marker represents a status emoji on an entry.
+type Marker int
+
+const (
+	MarkerAbandoned Marker = iota // :skull:
+	MarkerPaid                    // :heavy_dollar_sign:
+	MarkerWIP                     // :construction:
+)
+
+// Entry is a single link entry in the README.
+type Entry struct {
+	Name        string
+	URL         string
+	Description string
+	Markers     []Marker
+	Line        int    // 1-based line number in source
+	Raw         string // original line text
+}
+
+// Section is a heading with optional entries and child sections.
+type Section struct {
+	Title    string
+	Level    int // heading level: 1 = #, 2 = ##, etc.
+	Entries  []Entry
+	Children []Section
+	Line     int
+}
+
+// Document is the parsed representation of the full README.
+type Document struct {
+	Preamble []string  // lines before the first section
+	Sections []Section
+}