fix(harmonyos): honor jump to bottom while history loads

[wgqqqqq]

Summary

Clicking jump-to-bottom while HarmonyOS history was loading hid the button without scrolling. The pending history anchor also prevented the completion callback from following the tail. Explicit jumps now cancel that anchor and scroll immediately; normal tail following resumes when loading finishes, including on failure.

Add an isolated native history preview and a repeatable device check covering wide/compact content widths, live resizing, and successful/failed history responses. Mock the newly introduced RemoteLogger dependency in the host-stream test loader to restore the five failing paging tests.

Follow-up to #3206.

Validation

• Connected HarmonyOS device, real ChatTimeline with held mock history responses: all four combinations (wide/compact × success/failure) reproduced the missing tail and hidden button before the fix, then passed after the fix.
• node --test src/apps/mobile/harmonyos/tools/tests/host-stream.test.cjs src/apps/mobile/harmonyos/tools/tests/history-page-arrival.test.cjs: 11 passed.
• HarmonyOS debug HAP build and in-place device installation passed; returned the device to the normal app after testing.
• pnpm run harmony:architecture, pnpm run check:repo-hygiene, diff whitespace and Git object-size checks passed.

Device coverage exercises the native remote-controller UI with simulated history responses, not a live remote transport. Physical folding, remote workspaces, Peer Device Mode, and Detached Dispatch were not exercised. The rebase onto current main did not change the tested HarmonyOS sources.

AI-assisted implementation and review with Codex; focused host tests and native device checks completed, not a full platform matrix.