fix(wasm): #1323 dispatch timer builtins through mem_call bridge

[proggeramlug]

Summary

Fixes #1323 — on --target web/--target wasm, setTimeout/setInterval callbacks never fired. Top-level code ran, but every deferred callback was silently dropped.

Root cause

The timer builtins lower to Expr::ExternFuncRef { name: "setTimeout" } (via is_builtin_function in perry-hir), but the WASM emitter had no call-site handler for them. The generic ExternFuncRef arm in emit/expr/calls.rs looks the name up in func_name_map, doesn't find it (timers aren't user/FFI functions), and falls through to its else branch — which drops the args and pushes undefined. The timer was never scheduled.

The __memDispatch.set_timeout / set_interval / clear_timeout / clear_interval bridges in wasm_runtime.js already existed and were correct, and the names were already interned in string_collection.rs — only the emitter wiring was missing. (The rt.set_timeout direct-import variant is declared but never called.)

Fix

Intercept the four timer builtins in calls.rs before the generic ExternFuncRef arm and route them through the existing mem_call bridge, mirroring how fetch/closure_call dispatch:

• setTimeout/setInterval → set_timeout/set_interval with (closure, delay), returning the timer id.
• clearTimeout/clearInterval → clear_timeout/clear_interval with (id).

Missing args (e.g. setTimeout(fn)) are padded with undefined. Trailing setTimeout(fn, delay, ...args) extras are dropped for now (Node forwards them to the callback — out of scope here).

Test

Adds tests/wasm/23_timers.{ts,expected}: a self-clearing setInterval plus a setTimeout that prints top / tick / done.

Verified through the Node harness (tests/wasm/run_wasm_tests.sh, which evals the generated <script>s under real Node timers):

• With the fix: prints top, tick, done (interval fires once, clears itself, timeout fires) and Node exits cleanly.
• Without the fix (codegen change reverted): prints only top — reproducing the issue exactly.

The other 7 pre-existing wasm-suite failures (objects/arrays, higher-order, map/set, regex/date, class-field-splice, module-splice, ffi-imports) are unchanged by this PR; confirmed by running the suite with and without the codegen change.