Initial commit: capability prober + design docs

Monorepo root for Echolot. Contains the no-root capability prober
(Kotlin/Compose, app.echo_lot.prober) and the four design docs that act
as the contract for the production app and the Go server.

LICENSE is deliberately absent — still undecided, see docs/build-status.md.

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

echolot-prober/.gitignore

@@ -0,0 +1,10 @@
+.gradle/
+build/
+/local.properties
+/.idea/
+*.iml
+.DS_Store
+/captures
+.externalNativeBuild
+.cxx
+/app/release