[FEATURE] --all flag on claude resume

### Preflight Checklist

- [x] I have searched [existing requests](https://github.com/anthropics/claude-code/issues?q=is%3Aissue%20label%3Aenhancement) and this feature hasn't been requested yet
- [x] This is a single feature request (not multiple features)

### Problem Statement

IMO, typing claude resume (without --) should run /resume (I don't see the point of claude with a single positional argument running claude and piping that single word into claude as a prompt, it makes lierally no sense)

And then claude resume --all should be equivalent to entering a claude session, typing /resume and clicking Ctrl-A.

### Proposed Solution

-

### Alternative Solutions

_No response_

### Priority

Medium - Would be very helpful

### Feature Category

CLI commands and flags

### Use Case Example

_No response_

### Additional Context

_No response_

No files, tests, or entry points are named. Start by locating the CLI handling for `claude resume` and the existing `/resume` behavior, then verify that the positional command and `--all` flow match the requested session behavior.

Written by the indexing model from the issue text.