Add setTimeout/setInterval support to the QuickJS plugin runtime

[fluffy637]

Fixes #190 (and likely most "plugin works on mobile but returns 0 streams on desktop" reports).

Problem: plugins written for the mobile app commonly call setTimeout (fetch timeouts, retry backoff). The QuickJS runtime injects fetch, AbortController, etc., but no timers — so those plugins throw ReferenceError: setTimeout is not defined inside their own try/catch blocks and silently return zero streams on desktop.

Fix:

• New TimerBridge host module exposing an async __native_delay binding backed by kotlinx.coroutines.delay (capped at the plugin timeout, cancelled with the QuickJs instance)
• Timer polyfill in JsBindings (setTimeout/clearTimeout/setInterval/clearInterval/setImmediate) built on __native_delay, with JS-side cancellation and exception containment
• Desktop test covering callback firing, extra args, and cancellation

Same approach as the official quickjs-kt setTimeout sample.

Note: the JS polyfill was validated standalone (firing, cancellation, intervals, exception containment); the Kotlin side follows the existing HostModule pattern but was not compiled locally — please let CI run.

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