Fix mobile-web image attachment submits

[patroza]

What changed

• read the latest composer draft directly from the store when submitting, so an image selected through Tim Smart’s compact mobile upload button cannot be omitted before React synchronizes its mirror refs
• use the same latest-draft snapshot for terminal and element context
• install the Electron runtime in the macOS static-analysis job before running the focused Open With test

Why

On iPhone, the native image picker updates our persisted composer draft synchronously. The submit handle previously read a ref updated later by a React effect, creating a race where the selected image appeared in state but the immediate send used an empty attachment list.

The integration CI failure was unrelated to Expo: the macOS job globally skips Electron downloads and then imported Electron in the focused test without running the repository repair/install step.

Verification

• pnpm exec vp check apps/web/src/components/chat/ChatComposer.tsx
• pnpm exec vp test run apps/web/src/composerDraftStore.test.ts (74 passed)
• pnpm exec vp run --filter @t3tools/web typecheck
• isolated app server launched; collaborative browser verification was blocked by the preview tab retaining an invalid prior session credential