core: prevent scope parent-chain cycles when reusing pooled frames

- Scope.resetForReuse: fully detach before re-parenting (clear state, parent=null, new frameId), then validate with ensureNoCycle and assign parent/args/pos/thisObj
- ScopePool.borrow (JVM/Android/JS/Native/Wasm): defensive fallback to fresh Scope allocation if resetForReuse detects a cycle
- docs: add docs/fix-scope-parent-cycle.md describing the change and expectations
- test: add ScopeCycleRegressionTest to ensure instance method call pattern does not crash and returns "ok"

lynglib/src/wasmJsMain/kotlin/net/sergeych/lyng/ScopePoolWasm.kt

@@ -29,12 +29,18 @@ actual object ScopePool {
 
     actual fun borrow(parent: Scope, args: Arguments, pos: Pos, thisObj: Obj): Scope {
         val s = if (pool.isNotEmpty()) pool.removeLast() else Scope(parent, args, pos, thisObj)
-        if (s.parent !== parent || s.args !== args || s.pos !== pos || s.thisObj !== thisObj) {
-            s.resetForReuse(parent, args, pos, thisObj)
-        } else {
-            s.frameId = nextFrameId()
+        return try {
+            if (s.parent !== parent || s.args !== args || s.pos !== pos || s.thisObj !== thisObj) {
+                s.resetForReuse(parent, args, pos, thisObj)
+            } else {
+                s.frameId = nextFrameId()
+            }
+            s
+        } catch (e: IllegalStateException) {
+            if (e.message?.contains("cycle") == true && e.message?.contains("scope parent chain") == true) {
+                Scope(parent, args, pos, thisObj)
+            } else throw e
         }
-        return s
     }
 
     actual fun release(scope: Scope) {