Fix sidebar workspace session loading

[LIUXIN557]

Summary

• start visible workspace session requests alongside auxiliary pinned-session work
• keep loaded empty workspaces from returning to the loading state during refresh
• discard stale compact responses after a newer full expansion and observe early request failures immediately

Verification

ode web/src/lib/sidebarWorkspaceSessions.test.js

• pnpm test
• pnpm build
• Chrome end-to-end checks for empty workspace loading, injected request failure, and compact/full response race