fix(buddy): address CodeRabbit review findings

- buddy.ts: return type Promise<null> → Promise<React.ReactNode>
  to match LocalJSXCommandCall interface (CompanionCard path returns
  ReactElement, not null).
- CompanionCard.tsx: clamp stat value to 0..100 before .repeat()
  to prevent negative count runtime error on out-of-range values.

Import path alias suggestions (src/ vs ../) dismissed — project
convention uses relative paths (verified against color.ts, help.ts).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/commands/buddy/buddy.ts

@@ -71,7 +71,7 @@ export async function call(
   onDone: LocalJSXCommandOnDone,
   context: ToolUseContext & LocalJSXCommandContext,
   args: string,
-): Promise<null> {
+): Promise<React.ReactNode> {
   const sub = args?.trim().toLowerCase() ?? ''
   const setState = context.setAppState