app: installable APK — core-probe (device-tier) + Compose UI

First assembling build of the production app. Android toolchain mirrors
the prober (AGP 9 built-in Kotlin; applying kotlin.android too
double-registers the kotlin extension — the one gotcha).

core-probe (Android lib): Probe→core-measurement Test abstraction;
NetworkInventory (LinkProperties→networks[]), LinkSnapshotProbe,
per-network IcmpProbe (ported from the prober's validated logic).

app (Compose): RunViewModel orchestrates probes into a MeasurementDocument
with a §7.3 summary + first-pass findings; UI renders traffic lights,
networks, tests, findings; JSON export. Rotation-safe (ViewModel).
App-tier only; server-facing (core-engine) + Shizuku are additive
follow-ups. Debug APK 9.5 MB, assembles clean.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

echolot-app/app/.gitignore

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