refactor: isolate deno_core into windmill-runtime-nativets subcrate (#7848)

* refactor: isolate deno_core into windmill-runtime-nativets subcrate

Remove deno_core from flow eval and isolate nativets V8 runtime into a
dedicated subcrate so deno_core compilation no longer blocks
windmill-worker or windmill-api.

- Create windmill-jseval crate: QuickJS-based JS eval for flow
  expressions and batch rerun, extracted from windmill-worker
- Create windmill-runtime-nativets crate: all deno_core/V8 deps and
  nativets script execution, with build.rs snapshot generation
- Simplify windmill-worker: remove all deno_* direct deps, empty
  build.rs, gate nativets behind optional dep
- Update windmill-api: use windmill-jseval for batch rerun instead of
  deno_core, remove deno_core feature entirely
- Add nativets integration tests (nativets_jobs.rs) and parallel
  stress test (nativets_stress.rs, 8 workers x 200 jobs)
- Remove dead code: deno flow eval path, USE_QUICKJS env var,
  parity tests (replaced with 63 standalone expected-value tests)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix: address PR review feedback for deno_core isolation

- Deduplicate unsafe_raw() into windmill-common/src/utils.rs (single source)
- Delete orphaned runtime.js and windmill-client.js from windmill-worker/src/
- Fix operator precedence in windmill-jseval with explicit parentheses
- Remove unnecessary return keyword in heap limit callback
- Remove redundant as usize casts
- Remove ~150 lines of commented-out code from runtime.js
- Remove commented-out #[cfg] in build.rs

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* otel ee

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

backend/windmill-common/src/utils.rs

@@ -974,6 +974,14 @@ pub async fn get_custom_pg_instance_password(db: &DB) -> Result<String> {
     )
 }
 
+/// Convert a JSON string to a `Box<RawValue>` without validation.
+///
+/// # Safety
+/// The caller must ensure the string is valid JSON.
+pub fn unsafe_raw(json: String) -> Box<serde_json::value::RawValue> {
+    unsafe { std::mem::transmute::<Box<str>, Box<serde_json::value::RawValue>>(json.into()) }
+}
+
 // Avoid JSON parsing for merging raw JSON values into an object
 pub fn merge_raw_values_to_object(
     pairs: &[(String, Box<serde_json::value::RawValue>)],