fix(tauri): bypass WebView CORS for packaged R2/S3 apps

Preserve aws4fetch Request headers in the shell fetch interceptor, and
proxy cross-origin HTTP through a native reqwest command so Windows/Android
builds work even when remote CORS only allows web origins.

template/src-tauri/Cargo.toml

@@ -16,6 +16,9 @@ tauri-build = { version = "2", features = [] }
 tauri = { version = "2", features = [] }
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
+reqwest = { version = "0.12", default-features = false, features = ["rustls-tls", "gzip", "brotli", "deflate"] }
+base64 = "0.22"
+
 
 [profile.release]
 codegen-units = 1