improve error management with thiserror use

- add thiserror dependency
- use distinct Error enum in lib and server

Cargo.lock

@@ -512,6 +512,7 @@ dependencies = [
  "reqwest",
  "serde",
  "serde_json",
+ "thiserror",
  "tokio",
  "zip",
 ]
@@ -1495,6 +1496,26 @@ dependencies = [
  "windows-sys 0.52.0",
 ]
 
+[[package]]
+name = "thiserror"
+version = "1.0.61"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c546c80d6be4bc6a00c0f01730c08df82eaa7a7a61f11d656526506112cc1709"
+dependencies = [
+ "thiserror-impl",
+]
+
+[[package]]
+name = "thiserror-impl"
+version = "1.0.61"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "46c3384250002a6d5af4d114f2845d37b57521033f30d5c3f46c4d70e1197533"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "time"
 version = "0.3.36"