Register py_event_loop module in OWN_GIL subinterpreters

Fix reactor tests failing in OWN_GIL mode by registering the
py_event_loop module during OWN_GIL thread initialization.

The reactor functions call get_module_state() to access the reactor
cache, which requires the py_event_loop module to exist. Without this,
get_module_state() returns NULL and reactor operations fail.

Enable the previously skipped py_reactor_context tests now that
OWN_GIL reactor dispatch works correctly.

Author: benoitc

c_src/py_nif.c

@@ -2824,6 +2824,14 @@ static void *owngil_context_thread_main(void *arg) {
         return NULL;
     }
 
+    /* Register py_event_loop module for reactor support */
+    if (create_py_event_loop_module() < 0) {
+        PyErr_Print();
+        Py_EndInterpreter(ctx->own_gil_tstate);
+        atomic_store(&ctx->thread_running, false);
+        return NULL;
+    }
+
     /* Create namespace dictionaries */
     ctx->globals = PyDict_New();
     ctx->locals = PyDict_New();

test/py_owngil_features_SUITE.erl

@@ -947,9 +947,6 @@ reactor.set_protocol_factory(EchoProtocol)
 
 %% @doc Multiple connections in owngil reactor
 owngil_reactor_multiple_conn_test(_Config) ->
-    {skip, "py_reactor_context OWN_GIL integration needs investigation"}.
-
-owngil_reactor_multiple_conn_test_DISABLED(_Config) ->
     SetupCode = <<"
 import erlang.reactor as reactor
 
@@ -1011,9 +1008,6 @@ reactor.set_protocol_factory(CounterProtocol)
 
 %% @doc async_pending pattern in owngil reactor
 owngil_reactor_async_pending_test(_Config) ->
-    {skip, "py_reactor_context OWN_GIL integration needs investigation"}.
-
-owngil_reactor_async_pending_test_DISABLED(_Config) ->
     SetupCode = <<"
 import erlang.reactor as reactor
 
@@ -1079,9 +1073,6 @@ result = {
 
 %% @doc Protocol factory isolation between owngil contexts
 owngil_reactor_isolation_test(_Config) ->
-    {skip, "py_reactor_context OWN_GIL integration needs investigation"}.
-
-owngil_reactor_isolation_test_DISABLED(_Config) ->
     EchoSetup = <<"
 import erlang.reactor as reactor