refactor: split into independent trx-server and trx-client binaries

Delete trx-bin (all-in-one) and trx-bin-common (shared lib). Each binary
now has its own config, plugins, and helper modules inlined.

- trx-server: backend-only daemon with ServerConfig (general, rig, behavior)
  no frontend dependencies
- trx-client: remote client with ClientConfig (general, remote, frontends)
  includes all frontend support (http, rigctl, http-json, qt)
- Dedicated config files: trx-server.toml / trx-client.toml

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Cargo.lock

@@ -1873,7 +1873,7 @@ dependencies = [
 ]
 
 [[package]]
-name = "trx-bin"
+name = "trx-client"
 version = "0.1.0"
 dependencies = [
  "clap",
@@ -1882,11 +1882,9 @@ dependencies = [
  "serde",
  "serde_json",
  "tokio",
- "tokio-serial",
  "toml",
  "tracing",
  "tracing-subscriber",
- "trx-backend",
  "trx-core",
  "trx-frontend",
  "trx-frontend-http",
@@ -1961,6 +1959,23 @@ dependencies = [
  "trx-frontend",
 ]
 
+[[package]]
+name = "trx-server"
+version = "0.1.0"
+dependencies = [
+ "clap",
+ "dirs",
+ "libloading",
+ "serde",
+ "tokio",
+ "tokio-serial",
+ "toml",
+ "tracing",
+ "tracing-subscriber",
+ "trx-backend",
+ "trx-core",
+]
+
 [[package]]
 name = "typenum"
 version = "1.19.0"