docs: update shell-mode spec for single-enter slash command submission

Document that slash commands now submit on Enter (except /title) rather than requiring Tab first.

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Co-Authored-By: Continue <[email protected]>
Co-authored-by: nate <[email protected]>

Author: 3 people

extensions/cli/spec/shell-mode.md

@@ -27,6 +27,8 @@ Interaction with other input helpers
   - "/" slash command UI is disabled.
 - When in slash command mode (input starts with /):
   - "@" file search suggestions are disabled.
+  - Enter submits the highlighted slash command directly (except /title, which requires Tab to select first).
+  - Tab selects the highlighted command without submitting.
 
 Submission behavior