fix: enable getrandom js feature for WASM compilation

The getrandom crate (transitive dep via rand/argon2) requires the
"js" feature flag to compile for wasm32-unknown-unknown targets.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Cargo.lock

@@ -552,8 +552,10 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ff2abc00be7fca6ebc474524697ae276ad847ad0a6b3faa4bcb027e9a4614ad0"
 dependencies = [
  "cfg-if",
+ "js-sys",
  "libc",
  "wasi",
+ "wasm-bindgen",
 ]
 
 [[package]]
@@ -625,6 +627,7 @@ name = "idfoto-wasm"
 version = "0.1.0"
 dependencies = [
  "data-encoding",
+ "getrandom",
  "hmac",
  "idfoto-core",
  "js-sys",