Add LAN auto-discovery pairing with shared TLS certificate

Login screen now scans for Quest on LAN via NSD, auto-pairs by requesting
a pairing code from the Quest's TLS server, and falls back to manual code
entry. Both apps share a pinned self-signed certificate for secure LAN
communication. Also adds Moshi codegen KSP processor and disables cleartext.

app/build.gradle.kts

@@ -100,6 +100,7 @@ dependencies {
     implementation(libs.retrofit)
     implementation(libs.retrofit.converter.moshi)
     implementation(libs.moshi.kotlin)
+    ksp(libs.moshi.codegen)
     implementation(libs.okhttp)
     implementation(libs.okhttp.logging)