app: listen to what the segment says unprompted

Four passive collectors join long mode: SSDP (passive NOTIFY plus paced
M-SEARCH from the capture socket, so unicast replies land in the same
capture), LLMNR, NetBIOS-NS and WS-Discovery. All are periodic and sparse
by nature, which is exactly why they belong to a window rather than a
probe - a thirty-second run mostly hears silence and would report an
empty network as confidently as a quiet one.

NetBIOS reports unsupported on the app tier and says why: UDP 137 is
privileged. The decoder and evidence shape are tested and waiting for the
Shizuku tier; a recorded reason beats a missing test.

Silence without a multicast lock or a group join is PARTIAL, never OK -
that case is a fact about this app, not about the network. Hostnames,
banners and device UUIDs are classified in core-privacy so the anonymizer
treats them like every other identifier rather than letting a neighbour's
device model ride out in an upload.

No active WSD Probe and no NBSTAT sweep: the app listens to what a
network broadcasts, it does not announce itself to strangers or
interrogate its neighbours.

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

echolot-app/core-probe/build.gradle.kts

@@ -28,4 +28,9 @@ dependencies {
     implementation(project(":core-measurement"))
     implementation(libs.kotlinx.serialization.json)
     implementation(libs.kotlinx.coroutines.android)
+    // JVM unit tests for the pure wire-format decoders (DiscoveryParsers.kt) against realistic and
+    // deliberately malformed payloads — no device, no Android runtime. Same setup as core-shizuku's
+    // dump-parser tests: JUnit 4, because that is what AGP's unit-test source set runs.
+    testImplementation(libs.kotlin.test.junit)
+    testImplementation(libs.junit4)
 }