Gradle Build Cache Deep Dive

Walk through how Gradle's build cache actually works internally — content hashing, relocatability requirements, and the specific cache poisoning scenarios that silently break builds. Cover remote cache setup with GCS/S3, cache key debugging with build scans, and the KMP-specific gotchas (cinterop tasks, expect/actual mismatches) that cause unnecessary cache misses. Include real metrics from a multi-module KMP project showing before/after CI times.