[Feature][Android] Add fixed Lynx viewport support

[Huxpro]

Summary

Add a typed fixed Lynx viewport for Android Sparkling pages, preserving the historical physical-pixel width + height behavior without exposing LynxViewBuilder.

This is the second layer of the Android compatibility stack and depends on #119.

Related issues

Standalone compatibility enhancement for host containers migrating legacy Lynx launch URLs.

Changes

• Add SparklingLynxViewport for positive physical-pixel dimensions.
• Parse canonical width and height with Legacy-compatible last-valued duplicate semantics.
• Resolve programmatic init params, context values, and scheme values in that order.
• Apply exact preset measure specs before LynxView construction.
• Apply matching child layout params while preserving full-size defaults when unset or invalid.
• Add unit coverage and a device instrumentation fixture that can wait for real first-screen rendering when the bundle is packaged.
• Document the scheme and Android APIs in English and Chinese.

How to test

• cd packages/playground/android && ./gradlew :sparkling:testDebugUnitTest --tests com.tiktok.sparkling.SparklingLynxViewportTest --tests com.tiktok.sparkling.SparklingViewTest --tests com.tiktok.sparkling.utils.SchemeParserTest --tests com.tiktok.sparkling.hybridkit.lynx.LynxKitInitParamsTest --no-daemon
• cd packages/playground/android && ./gradlew :app:assembleDebugAndroidTest --no-daemon
• PATH=/tmp/sparkling-ktlint-bin:$PATH scripts/lint.sh kotlin

Cloud-device execution of FixedLynxViewportInstrumentedTest will be attached before this PR is considered complete.

Stack

• [Feature][Android] Add pre-load Lynx view lifecycle #119 pre-load Lynx view lifecycle
• This PR: fixed viewport

Checklist

• I read CONTRIBUTING.md.
• I explained why this is standalone.
• I ran relevant checks.
• I updated docs.
• I added tests.

Device validation complete

The durable SG1 + Lynx Sandbox acceptance matrix is now available in #131. Exact validated commit: 8a2b3ea99eaa342e2f1ebfe716aefbb44f411fbb. On a fresh aries_10 device (Android 10 / API 29), all 9 tests passed, including real first-screen rendering, fixed 320x480, shared density 3.25 across two independent Lynx views, PART_ON_LAYOUT, typed template fetch invocation, orientation, retry recovery, and unsafe configuration rejection. The runner dynamically leases/releases the device and archives logs/screenshots/hashes. Evidence archive on SG1: /tmp/sparkling-android-device-acceptance-8a2b3ea.tar.gz (SHA-256 09acd64b4b63988b61e7f4f2ff11f3f7b4b4770bd3ef74a973db6dda0c9e242c).

Expanded durable device validation

The checked-in SG1 + Lynx Sandbox matrix in #131 now validates exact commit df875a87541d587ab8aa84a86600c0610f9e44c7 with 10/10 PASS on aries_10 (Android 10 / API 29). Added runtime coverage includes: the pre-load listener observing a ready bridge before template fetch; the global per-page fetcher factory; real first-screen rendering for ALL_ON_UI, MOST_ON_TASM, PART_ON_LAYOUT, and safe MULTI_THREADS; and full-page fixed-viewport + MULTI_THREADS rejection before Activity launch or transfer-station save. The runner requires a clean exact HEAD and fails closed unless Sandbox release confirms the leased serial. Evidence: /tmp/sparkling-android-device-acceptance-df875a8; archive SHA-256 712a3b83dbd78eabeae9afc0766b5b191cee0bff10e515967b3ae9f46c4feb98.