initialize generic rms-software repository

Add the reusable RMS core application (server, web UI, plugins, tests, tools) with generic defaults, GPL licensing, and maintainer context documentation so deployments can consume this repo as software source independent of station-specific overlays.

plugins/rms.tx.audio.core/manifest.json

@@ -0,0 +1,16 @@
+{
+  "id": "rms.tx.audio.core",
+  "name": "TX Audio Core",
+  "version": "1.0.0",
+  "apiVersion": "1.0",
+  "capabilities": [
+    "tx.audio"
+  ],
+  "settingsSchema": {
+    "type": "object",
+    "properties": {
+      "backendCapability": { "type": "string", "default": "tx.audio.backend" }
+    },
+    "additionalProperties": false
+  }
+}