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/hooks/keyword-detector/index.ts

@@ -43,6 +43,7 @@ export function createKeywordDetectorHook() {
       }
 
       const context = messages.join("\n")
+      log(`[keyword-detector] Injecting context for ${messages.length} keywords`, { sessionID: input.sessionID, contextLength: context.length })
       const success = injectHookMessage(input.sessionID, context, {
         agent: message.agent,
         model: message.model,