[FEATURE] Add deep research mode as a /research slash command

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

I love the deep research tool, but I have to invoke it in the webUI and copy/paste or download & import the reports into repository for claude code; it then has to "re-read" the report (when it's still in-memory in the web instance). I really wish I could invoke a deep research subagent from directly within claude code with a slash command so I didn't have to switch interface and move files around. Seems like a straightforward implementation.

Proposed Solution

I'd like to be able to enter /research and complete deep research directly within claude code, and have the reports saved into the active repository.

Alternative Solutions

I have to switch to browser or claude app, invoke research mode, rebuild context of my project scope, then copy/download the research to paste/import into calude code session.

Priority

Medium - Would be very helpful

Feature Category

CLI commands and flags

Use Case Example

1. I'm developing a new feature that needs research for one of many reasons:

• I need to research existing implementations to see if there are existing libraries I can use
• I need the implementation to reference public documents for dependent requirements/formulas
• I'm exploring a novel architecture and need to steelman it against known implementations

1. I want the results of the research to directly impact the plan and behavior of my claude code session, so I can apply the learnings to the project in which I invoked the research.
2. Claude code can use a subagent to access search tools available to the deep research agent, which will complete the research report and save it as a markdown file, and then resolve actionable elements of the research into the project plan/task list (after some user discussion)
3. I never had to leave claude code to do this.

Additional Context

_No response_