chore(interview): add command for detailed plan interviews

Introduce a new command that allows users to conduct in-depth interviews about a specified plan file. The command utilizes the AskUserQuestionTool to facilitate comprehensive discussions on various aspects of the plan, ensuring questions are insightful and not obvious. The final output will be written to a specified file.

.claude/commands/interview.md

@@ -0,0 +1,11 @@
+---
+description: Interview me about the plan
+argument-hint: [plan]
+model: opus
+---
+
+Read this plan file $1 and interview me in detail using the AskUserQuestionTool about
+literally anything: technical implementation, UI & UX, concerns, tradeoffs, etc.
+but make sure the questions are not obvious.
+
+Be very in-depth and continue interviewing me continually until it’s complete, then write the spec to the file.