fix: resolve NPE, type inference, and variable hiding issues

1. FunctionSignature.matchAgainstArgs: Remove duplicate matchAgainstSupertype
   call that was added for debug logging but passed potentially-null mapping
   to the second call, causing NPE on generic static method calls.

2. FuncLink.create: Only add function's own type parameters as type variables
   in the mapping. Enclosing structure type params (class/module) are resolved
   through receiver type matching, not through argument inference.

3. FunctionSignature.fromNameLink: Only add function definition's own type
   parameters as type variables, not enclosing structure params. This prevents
   module type params from appearing as unbound inference variables.

4. FuncLink.withTypeArgBinding: Also check if any type params are being bound
   (even when types don't change structurally, e.g., T bound to itself within
   a generic module) to ensure the FuncLink is updated.

5. WurstValidator: Downgrade variable-hides-superclass-variable from error to
   warning, matching pre-wurstscript#1098 behavior.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: Donach

de.peeeq.wurstscript/src/main/java/de/peeeq/wurstscript/types/FunctionSignature.java

@@ -247,12 +247,12 @@ public WurstType getVarargType() {
             WurstType pt = getParamType(i);
             WurstType at = argTypes.get(i);
             VariableBinding before = mapping;
-            VariableBinding after = at.matchAgainstSupertype(pt, location, mapping, VariablePosition.RIGHT);
+            mapping = at.matchAgainstSupertype(pt, location, mapping, VariablePosition.RIGHT);
+            VariableBinding after = mapping;
             WLogger.trace(() -> "[IMPLCONV]   vb " + System.identityHashCode(before)
                 + " -> " + (after == null ? "null" : System.identityHashCode(after))
                 + " sameObj=" + (before == after)
                 + " pt=" + pt + " at=" + at);
-            mapping = after;
             if (mapping == null) return null;
 
         }

de.peeeq.wurstscript/src/main/java/de/peeeq/wurstscript/validation/WurstValidator.java

@@ -1861,7 +1861,7 @@ private void checkFieldShadowing(ClassDef c) {
                     ClassDef superOwner = (ClassDef) owner;
                     if (isStrictSuperclassOf(superOwner, c)) {
                         // produce the requested error text
-                        def.addError("Variable " + name + " in class " + c.getName()
+                        def.addWarning("Variable " + name + " in class " + c.getName()
                             + " hides variable " + name + " from superclass " + superOwner.getName());
                         // one error per conflicting ancestor is enough
                         break;

de.peeeq.wurstscript/wurst_run.args

@@ -0,0 +1,3 @@
+-runcompiletimefunctions
+-injectobjects
+-stacktraces