Updated Backend Model | Prompt Refining | Benchmarking

[Bhagat-Atul]

Changed:

• Backend default GEMINI_MODEL to gemini-3.5-flash in backend/main.py:35
• Android default/model catalog to Gemini 3.5 Flash
• Backend README deploy/env examples
• Android proxy test fixtures
• Version tracking: release/app/backend/analysis/ui now at 1.0.1
• Gradle default versionName=1.0.1, versionCode=2

Verification passed:

• .venv/bin/python -m pytest backend/tests/test_app.py backend/tests/test_benchmark_analyze.py -q
• ./gradlew :app:testDebugUnitTest :app:verifySourceTreeForBuild