TL;DR: "Load more" looked random because the backend and sidebar disagreed on what "newest" meant.

From the actual local DB investigation, the API was selecting/paginating root sessions by created time, but the app sidebar displays sessions by updated time. That means a session created days ago but touched recently can be outside the first page, then appear near the top after clicking Load more. Concrete example from the repro data: "fix: ResizeObserver crash" was created-rank 22 but updated-rank 6, so it appeared around position 6 only after increasing the loaded page.

This PR keeps the API default unchanged for compatibility, but gives app consumers a way to ask for the ordering they actually display.

Summary:

• Add optional v2 session list sort=created|updated without changing the default created sort.
• Include sort in session cursors so pagination stays on the selected timestamp.
• Make the app sidebar session loader request updated sorting and trim by updated order.
• Regenerate OpenAPI/JS SDK.

Tests:

• bun test src/context/global-sync.test.ts src/context/global-sync/session-trim.test.ts (packages/app)
• bun test --timeout 30000 test/server/httpapi-session.test.ts (packages/opencode; first run hit Windows cleanup flake, rerun passed)
• bun test --timeout 30000 test/server/httpapi-query-schema-drift.test.ts (packages/opencode)
• bun run script/httpapi-exercise.ts --mode coverage --fail-on-missing --fail-on-skip (packages/opencode)
• bun typecheck (packages/opencode, packages/app, packages/sdk/js)
• pre-push bun turbo typecheck