Implement Unicode text formatter plugin

- Add unicode-maps.ts with BOLD_MAP, ITALIC_MAP, BOLD_ITALIC_MAP from Unicode Sans-Serif ranges
- Add formatter.ts with transformText(text, style) using the maps
- Add commands.ts registering three editorCallback commands (bold, italic, bold-italic)
- Replace sample plugin boilerplate in main.ts with UnicodeFormatterPlugin wired to registerCommands
- Update manifest.json with correct id, name, and description
- Delete unused settings.ts boilerplate

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

src/formatter.ts

@@ -0,0 +1,14 @@
+import { BOLD_MAP, ITALIC_MAP, BOLD_ITALIC_MAP } from "./unicode-maps";
+
+export type FormatStyle = "bold" | "italic" | "bold-italic";
+
+const STYLE_MAPS: Record<FormatStyle, Record<string, string>> = {
+    "bold": BOLD_MAP,
+    "italic": ITALIC_MAP,
+    "bold-italic": BOLD_ITALIC_MAP,
+};
+
+export function transformText(text: string, style: FormatStyle): string {
+    const map = STYLE_MAPS[style];
+    return [...text].map(ch => map[ch] ?? ch).join("");
+}