Add transport-agnostic RPC layer for proxy app

Introduces yaak-rpc (shared RPC infrastructure) and yaak-proxy-lib
(proxy app logic decoupled from any frontend). A single Tauri command
dispatches all RPC calls through a typed router, with TypeScript types
auto-generated via ts-rs and a generic rpc() function for type-safe
calls from the frontend.

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

Cargo.lock

@@ -10306,11 +10306,12 @@ name = "yaak-app-proxy"
 version = "0.0.0"
 dependencies = [
  "log 0.4.29",
- "serde",
+ "serde_json",
  "tauri",
  "tauri-build",
  "tauri-plugin-os",
- "yaak-proxy",
+ "yaak-proxy-lib",
+ "yaak-rpc",
  "yaak-window",
 ]
 
@@ -10590,6 +10591,17 @@ dependencies = [
  "tokio-rustls",
 ]
 
+[[package]]
+name = "yaak-proxy-lib"
+version = "0.0.0"
+dependencies = [
+ "serde",
+ "serde_json",
+ "ts-rs",
+ "yaak-proxy",
+ "yaak-rpc",
+]
+
 [[package]]
 name = "yaak-proxy-models"
 version = "0.1.0"
@@ -10607,6 +10619,16 @@ dependencies = [
  "yaak-database",
 ]
 
+[[package]]
+name = "yaak-rpc"
+version = "0.0.0"
+dependencies = [
+ "log 0.4.29",
+ "serde",
+ "serde_json",
+ "ts-rs",
+]
+
 [[package]]
 name = "yaak-sse"
 version = "0.1.0"