Kotlin/Native Build Performance

Turn "the iOS build is slow" into a measured diagnosis and a small set of safe fixes. Two rules apply throughout:

1. Never trade away required release behavior. A faster local loop must not change what CI publishes.
2. Measure before and after with the same command and the same build state. An unmeasured fix is a guess.

Step 0: Classify the Slow Scenario

Establish four facts before editing anything: where (local or CI), what (debug feedback loop or release/distribution artifact), state (first build, clean, warm, or no-op), and phase (which tasks dominate the log). Then match the dominant symptom: