[feat] modularized backend with plugin architecture, added module-api, module-host, and summarizer crates, and integrated dynamic module loading into main.rs

backend-rust/Cargo.toml

@@ -1,5 +1,11 @@
 [workspace]
-members = ["crates/app", "crates/api"]
+members = [
+    "crates/app",
+    "crates/api",
+    "crates/module-api",
+    "crates/module-host",
+    "crates/modules/summarizer",
+]
 resolver = "2"
 
 [workspace.package]
@@ -22,7 +28,11 @@ sha2 = "0.10.9"
 hex = "0.4.3"
 readability = "0.3.0"
 scraper = "0.23.1"
+libloading = "0.8"
+async-trait = "0.1"
+once_cell = "1.19"
+num_cpus = "1.16"
 
-# Dev-only deps centralized (optional; you can also keep these inside each member)
+# Dev-only deps centralized (optional)
 tokio-test = "0.4"
 axum-test = "17.3"