feat: extract PR rendering to String() method using text/template

Co-authored-by: aider (openai/qwen3-coder:30b-a3b-q4_K_M) <aider@aider.chat>

contributions/gh.go

@@ -8,6 +8,7 @@ import (
 	"net/http"
 	"os"
 	"strings"
+	"text/template"
 )
 
 var ghc = http.Client{}
@@ -32,6 +33,21 @@ type PullRequest struct {
 	URL      string
 }
 
+// String returns a formatted string representation of the PullRequest
+func (pr PullRequest) String() string {
+	tmpl := template.Must(template.New("pr").Parse(`- Title: {{.Title}}
+  Body: {{.Body}}
+`))
+	
+	var buf bytes.Buffer
+	err := tmpl.Execute(&buf, pr)
+	if err != nil {
+		return "" // Return empty string on error
+	}
+	
+	return buf.String()
+}
+
 func GetPRs(org, username string, from string, to string) (map[string][]PullRequest, error) {
 	req, err := http.NewRequest(
 		http.MethodGet,