Suppress guest explicit GC with universal transform version

[H3nb]

Summary

• rewrite guest System.gc() and Runtime.gc() calls to an emulator-owned advisory bridge
• replace timing-only conversion metadata with one universal JLMod-Transform-Version marker
• make existing timing-marked MIDlets reconvert automatically and remove their legacy markers
• preserve Runtime.gc() receiver null semantics and keep normal ART allocation-pressure GC unchanged

Root cause

Green Farm calls System.gc() repeatedly from guest bytecode. On the tested Android 16 / HyperOS host with target SDK 35+, ART honored those calls as concurrent mark-compact collections, causing visible loading stalls and frequent object-address relocation. This is independent of the Memory Editor implementation in #109 and independent of emulation speed.

Universal reconversion contract

MidletTransformMetadata.TRANSFORM_VERSION is now the single compatibility version for all converter output and runtime bridge contracts. Future transformer changes only need to increment this value. The existing AppReconverter path will rebuild installed MIDlets with retained source before launch.

Validation

• CI-equivalent local lint, unit tests, screenshot validation, debug APK, and test APK: passed
• complete dexlib unit suite including JVM bytecode and real DEX verification: passed
• Emulator Release build with R8/lintVital: passed; both MidletSystem.gc bridge overloads are retained
• Android 16 device: legacy timing marker triggered AutoReconversionActivity and produced JLMod-Transform-Version: 1
• Green Farm converted DEX: 21 bridge GC callsites, 0 direct System.gc() callsites
• Green Farm runtime after reconversion: 0 explicit compacting GC during the measured launch window; loading animation visually smooth
• original shared Green Farm archive and descriptor restored byte-for-byte after the side-by-side test