Unlock screen orientation on Android (landscape support)

[jonocodes]

The Android app is currently locked to portrait mode via orientation: "portrait" in app.config.js, which sets android:screenOrientation="portrait" in the manifest. This means the app cannot rotate to landscape at all.

This becomes a problem when viewing images or screenshots inline in agent conversations. Without landscape mode, there's no way to get a wider viewport for viewing images, and there's no tap-to-expand or zoom functionality for assistant images (see PR #2342 which addresses the expand/zoom side).

Even without image viewing, landscape would be useful for:

• Reading long code blocks in agent output
• Using the app on tablets or foldables where landscape is natural
• Split-screen or multi-window usage

The layout system already has a compact vs. desktop breakpoint structure (useIsCompactFormFactor()), so the foundation for responsive layouts exists. The main work would be handling the transition at the 576px breakpoint so the desktop layout doesn't break on phone-width landscape screens.

Related issues:

• bug: App crashes upon switching orientation from landscape to portrait on iPadOS #1030 — App crashes on orientation switch (iPadOS)
• audit: platform/form-factor gates use wrong proxies #1047 — Form-factor gates use wrong proxies

It would be great to either unlock orientation entirely, or at minimum allow landscape for image viewing and code reading.