Fix diff screen hang/crash: stable DiffLine id + request timeout; bump to 1.5

DiffLine.id was a computed property returning a fresh UUID() on every access.
SwiftUI's ForEach requires stable identities; regenerating each read churned
the main thread, hanging the diff screen and eventually crashing. Store the
UUID once per line. Also add a 30s URLRequest timeout so a hung request can't
leave the 'Loading diff...' spinner forever. Bump to 1.5.

GiteaPR/Networking/GiteaClient.swift

@@ -71,6 +71,8 @@ struct GiteaClient {
         req.httpMethod = method
         req.setValue("token \(token)", forHTTPHeaderField: "Authorization")
         req.setValue("application/json", forHTTPHeaderField: "Accept")
+        // Bound every request so a hung call can't leave a spinner forever.
+        req.timeoutInterval = 30
         if let body {
             req.setValue("application/json", forHTTPHeaderField: "Content-Type")
             req.httpBody = body