fix(hook-message-injector): add validation to prevent empty message injection and improve logging

- Add content validation in injectHookMessage() to prevent empty hook content injection
- Add logging to claude-code-hooks and keyword-detector for better debugging
- Document timing issues in empty-message-sanitizer comments
- Update README with improved setup instructions

🤖 Generated with assistance of [OhMyOpenCode](https://github.com/code-yeongyu/oh-my-opencode)

src/features/hook-message-injector/injector.ts

@@ -71,6 +71,16 @@ export function injectHookMessage(
   hookContent: string,
   originalMessage: OriginalMessageContext
 ): boolean {
+  // Validate hook content to prevent empty message injection
+  if (!hookContent || hookContent.trim().length === 0) {
+    console.warn("[hook-message-injector] Attempted to inject empty hook content, skipping injection", {
+      sessionID,
+      hasAgent: !!originalMessage.agent,
+      hasModel: !!(originalMessage.model?.providerID && originalMessage.model?.modelID)
+    })
+    return false
+  }
+
   const messageDir = getOrCreateMessageDir(sessionID)
 
   const needsFallback =