feat(mobile): align native UI with HarmonyOS baseline

[wgqqqqq]

Summary

• add a HarmonyOS-derived mobile visual contract for semantic colors, typography, geometry, breakpoints, motion, component anatomy, and deterministic preview scenarios
• generate checked-in native tokens and preview data for ArkUI, Jetpack Compose, SwiftUI, and shared layout policy
• align conversation headers, message bubbles, composers, theme values, and compact/wide breakpoints across the three native apps
• add native preview launch paths plus a reusable desktop three-column comparison bench with screenshot dimensions, aspect warnings, overlays, grids, and HarmonyOS-relative full-frame pixel deltas

Fixes #

Type and Areas

Type:

Feature / UI/UX / tooling / docs

Areas:

Native mobile (HarmonyOS, Android, iOS), shared mobile layout policy, mobile design-system tooling

Motivation / Impact

HarmonyOS currently has the most complete native implementation. This makes it the explicit visual reference while keeping every platform on its native renderer. Stable visual facts now have one source contract, generated platform constants, deterministic gallery states, and a desktop comparison loop so future parity work is measurable instead of relying on memory.

Verification

• pnpm run mobile:ui:check — passed
• pnpm run mobile:architecture — passed
• pnpm run harmony:architecture — passed
• pnpm run theme:color-audit:all — passed
• pnpm run check:repo-hygiene — passed in a clean temporary worktree
• git diff --check upstream/1.0.0-explore...HEAD — passed
• Android: JAVA_HOME=/Applications/Android Studio.app/Contents/jbr/Contents/Home ./gradlew :app:assembleDebug — passed
• Shared mobile core: ./gradlew jvmTest — passed
• HarmonyOS: assembleHap --no-daemon — passed
• HarmonyOS: LocalTest test --no-daemon — passed
• iOS Simulator: xcodebuild -project BitFun.xcodeproj -scheme BitFun -sdk iphonesimulator ... build CODE_SIGNING_ALLOWED=NO — passed
• manually installed and captured the connected remote-conversation gallery on HarmonyOS, Android, and iOS emulators; the USB HarmonyOS device was not used

Reviewer Notes

• Native screenshots are intentionally local evidence and remain ignored; the comparison surface documents the conventional snapshot paths.
• The pixel delta is a non-gating full-frame trend metric. It includes status bars, notches, and gesture areas, while aspect mismatch is reported separately.
• This changes presentation only. Remote workspace, Peer Device Mode, and Detached Dispatch protocols are unaffected and were not exercised. The deterministic Remote Chat connected state was exercised locally on all three emulators.
• Generated native token/scenario files are checked in; edit the JSON contract and run pnpm run mobile:ui:generate rather than editing them directly.

Checklist

• This PR is focused and does not include secrets, temporary prompts, generated scratch files, or unrelated artifacts.
• Relevant verification is recorded above, or skipped checks are explained.
• User-facing strings, docs, and locales are updated where applicable.