fix(window): restore macOS titlebar drag by bumping gpui past #58947 revert

[whizz]

Problem

On macOS the main window cannot be moved by dragging the title bar (clicking + dragging the titlebar does nothing). Minimize/maximize and the Window menu still work.

Root cause

Not our title-bar code — it's the pinned gpui revision.

okena was locked to gpui 8432a26 (2026-06-11), which sits inside the 3-day window where Zed's #58947 ("Fix title bar clicks being delayed on macOS") was live before being reverted in #59214 (2026-06-12).

That patch implements the undocumented _opaqueRectForWindowMoveWhenInTitlebar SPI on gpui's macOS Metal view. For full-size-content windows — which we are, via appears_transparent: true → NSFullSizeContentViewWindowMask — it returns the entire view bounds as opaque app content. AppKit then treats no part of the window as a draggable titlebar, so window.start_window_move() becomes a no-op. Zed hit the exact same bug ("broke dragging the settings UI window") and reverted it the next business day.

Fix

• Bump gpui 8432a26 → fca2ccd4 (one day forward, past the revert). Moving the lock forward is always safe for this bug since the bad patch only ever existed in that 3-day window.
• The newer util crate (transitive via gpui) now calls smol::process::Child::adopt_raw_pid, which only exists in Zed's async-process fork. [patch] entries from a git dependency don't propagate, so mirror Zed's async-process / async-task patches in the workspace manifest (revs matched to the pinned gpui commit).

No Rust source changed — only Cargo.toml (+[patch.crates-io]) and Cargo.lock.

Verification

• cargo check --workspace — all okena crates incl. okena-app compile against the new gpui.
• Debug-built and ran on macOS (Darwin 25.5 / Tahoe): titlebar drag-to-move works, double-click-to-zoom still works.

Note for builders

Building gpui needs the Metal compiler. On a machine where xcode-select -p points at CommandLineTools, the shader build fails; select full Xcode (sudo xcode-select -s /Applications/Xcode.app) and, on Xcode 26, install the Metal Toolchain component (xcodebuild -downloadComponent MetalToolchain).