Extract tested domain layer, add a real build CI, fix missing gradlew

[jumincho]

A from-scratch-quality pass over the 2021 app, preserving the exact behaviour shown in the demo video (no UI/feature changes).

Real defect fixed

• The root gradlew / gradlew.bat launcher scripts were missing, so the documented ./gradlew assembleDebug could not run on a fresh clone. Restored them (gradlew executable). CI now requires both.

Testable domain layer

• Pulled the BMI and calorie-scoring rules out of the Fragment/ViewModel layer into a pure, framework-free domain/HealthMetrics so they can be unit tested on the JVM without a device.
• Behaviour is unchanged and pinned by HealthMetricsTest (7 tests, verified locally). The BMI formula had been duplicated across HomeViewModel and HomeFragment; both now delegate to one place.

CI that actually verifies

• The Verify workflow now builds the app (assembleDebug) and runs the JVM unit tests (testDebugUnitTest) on JDK 11 + Android SDK, on top of the existing structure/secrets checks. A throwaway FOOD_API_KEY satisfies the build-time guard; it never reaches a real request.

Cleanups (behaviour-neutral)

• Removed the original library author's ERROR-level debug logging left in production ("aa", "pheynix", "swifty" tags), now-unused TAG fields / Log imports, and the dead open() log branch in TodoActivity.
• Fixed the todayKcalSCore typo and dropped the write-only questionFlag field.
• Replaced the 2 + 2 placeholder unit test.

READMEs (KO / EN / ZH)

• Added a Verify CI badge and showed the new domain/ layer in the project tree. Content verified line-by-line across all three editions.

Note: this environment has no Android emulator, so runtime behaviour can't be exercised here — verification is by JVM unit tests + the CI compile/package. The change set is deliberately behaviour-preserving for exactly that reason.

https://claude.ai/code/session_011AjsUFiGcGPH71NuxTbHib

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