Always prefix lines in bullet conversion commands

Both bulletToArrow and bulletToEmdash now prepend the symbol to every
selected line, not just lines starting with "* ". Lines with "* " still
have the marker stripped before the prefix is added.

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

src/formatter.ts

@@ -19,12 +19,12 @@ export function cleanText(text: string): string {
 
 export function bulletToEmdash(text: string): string {
     return text.split("\n").map(line =>
-        line.startsWith("* ") ? "— " + line.slice(2) : line
+        line.startsWith("* ") ? "— " + line.slice(2) : "— " + line
     ).join("\n");
 }
 
 export function bulletToArrow(text: string): string {
     return text.split("\n").map(line =>
-        line.startsWith("* ") ? "→ " + line.slice(2) : line
+        line.startsWith("* ") ? "→ " + line.slice(2) : "→ " + line
     ).join("\n");
 }