Fix: Add -p flag when spawning Claude with a prompt

Without -p flag, Claude expects input from stdin and fails with:
"Input must be provided either through stdin or as a prompt argument"

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

src/claude-spawner.ts

@@ -78,7 +78,9 @@ export async function spawnClaude(
     const projectEnv = loadEnvFile(project.path);
 
     // Spawn Claude Code
-    const claudeProcess = spawn('claude', initialPrompt ? [initialPrompt] : [], {
+    // Use -p flag to pass prompt, otherwise Claude expects stdin
+    const args = initialPrompt ? ['-p', initialPrompt] : [];
+    const claudeProcess = spawn('claude', args, {
       cwd: project.path,
       stdio: ['ignore', 'pipe', 'pipe'],
       detached: true,