fix(mobile): align native login panels and QR connection flows

[wgqqqqq]

Summary

Align native Android, iOS, and HarmonyOS connection flows, including compact GitHub login panels and app-owned QR scanning on Android.

• Present login as a bottom-aligned, content-sized panel: 280 logical units high by default, 560 maximum width, 8 outer margin and 28 corner radius. Share geometry through the mobile design contract and generated native tokens.
• Align title, supporting copy, action positions, close glyphs and button appearance across all three platforms. Grow or scroll for accessibility text and errors; retain native modal dismissal and an iOS 16.0–16.3 sheet fallback.
• Replace Android's external Google scanner UI with an inline CameraX / bundled ML Kit scanner. Release the camera for manual pairing and dismissal, resume on return, and handle camera permission changes.
• Preserve the connection chooser and direct-scan entry points, and remove the duplicate shared account-state constructor that blocked builds.

Type and Areas

Type: UI/UX, bug fix, tests

Areas: Native Android, iOS, HarmonyOS, mobile design system, shared mobile account state

Motivation / Impact

The same connection action previously opened different layouts across mobile platforms. GitHub login also occupied nearly the whole screen despite having only a short explanation and one action. All three now use the same compact panel geometry; Android QR scanning stays inside the app and follows the existing native scanner layout.

Measured native screenshots at a 402 × 874 logical viewport show a 386 × 280 login panel on all three platforms. Wide layouts use 560 × 280 panels. System safe-area offsets and native font rasterization remain platform-specific; this is not a claim of identical full-screen pixels.

Verification

Passed during implementation:

• pnpm run mobile:ui:check
• pnpm run mobile:architecture
• pnpm run theme:color-audit:all — all 23 selected surfaces
• Android: ./gradlew :app:assembleDebug :app:testDebugUnitTest
• Android: ./gradlew :app:connectedDebugAndroidTest -Pandroid.testInstrumentationRunnerArguments.class=com.openbitfun.mobile.app.ConnectionSheetChromeTest — 3 tests, including phone/wide panel geometry, action positions, CJK line boxes and click handling
• Android: focused InlineQrDecoderTest — bundled decoder recognizes a generated QR fixture and rejects a blank image
• iOS: xcodebuild -project OpenBitFun.xcodeproj -scheme OpenBitFun -destination 'platform=iOS Simulator,name=iPhone 17 Pro' CODE_SIGNING_ALLOWED=YES CODE_SIGNING_IDENTITY=- build
• HarmonyOS: after sourcing scripts/ohos-env.sh, "$HVIGORW" --mode module -p product=default -p module=entry@default assembleHap --no-daemon
• git diff --check

Manual simulator checks: Android phone/wide layouts and 1.5× text; iPhone/iPad and accessibility-large text; HarmonyOS folded/unfolded transitions while the login panel is open; dismissal/back navigation; camera permission-denied UI; Android camera active → released during manual pairing → resumed → released on close.

Reviewer Notes

Changes affect the local native presentation of remote-control entry points. Real GitHub authorization and end-to-end remote workspace, Peer Device, and Detached Dispatch connections were not exercised. No credentials, user data migrations or wire-protocol changes are included. Local screenshot reports are intentionally not committed.

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.