test: add 60s browser Mocha timeout (parity with engine repo)

Defensive headroom for js/wasm browser tests: Mocha's 2s default can trip a
heavier test under CI/parallel load before it finishes computing (the engine
repo hit this with its micrograd training demo). Set in the shared root
browser-test config so it applies to every module. No-op for the current fast
browser suites (tokenizer/validation/trace).

Verified CI-equivalent (fresh lock, 'clean assemble allTests' default mode):
BUILD SUCCESSFUL, kotlinStoreYarnLock clean. With -PincludeBrowserTests:
616 browser testcases, 0 failures. kotlin-js-store/yarn.lock is regenerated
per-build (not committed), so no lock change ships.

Author: michalharakal

build.gradle.kts

@@ -77,6 +77,11 @@ subprojects {
             if (name == "jsBrowserTest" || name == "wasmJsBrowserTest") {
                 failOnNoDiscoveredTests = false
                 enabled = includeBrowserTests
+                // Generous Mocha timeout (default is 2s): browser engines — wasmJs
+                // especially — run slower under CI/parallel load, so a heavier test
+                // can exceed the default before it finishes computing. Mirrors the
+                // engine repo's per-module bump. Harmless for the fast tests here.
+                useMocha { timeout = "60s" }
             }
         }
 }