[Feature]: Have Collapse Side Bar grant more screen real estate

[JKFerland]

Summary

Allot more screen space for the main portion of the app when we collapse the side bar content

Problem / goal

Currently, one can collapse the contents of the side bar, but they gain no benefit in doing so. The side bar remains in place, just without workspaces

Primary user(s)

• [ X ] Bob (IT / power user)
• [ X ] Susan (non-technical)
• Other team roles

OpenCode primitive alignment

N/A

Alignment with VISION/PRINCIPLES/PRODUCT

The changes align with Vision (premium experience layer), Principles (no new engine parallel; disclosure; testable UI), and Product (desktop chat-first consumption, shared mental model for Bob and Susan).

Testability

• Open the app
• Press the chevron in the side bar

Ready to build it yourself?

Yes

Additional context

No response