qml: defer ReactiveListModel/ReactiveObject initial fetch to componentComplete()

setBaseUrl() and setSource() used to fire refresh() inline as soon as
both `baseUrl` and `source` were populated — but setToken() never
triggered a refresh. QML evaluates literal property assignments before
bindings to other objects' properties, so a model declared with
literal `source` plus bindings to `BackendConnection.url` /
`BackendConnection.token` (the exact shape of make:bridge:window's
output) could fire its GET *before* the `token` binding had landed.
The unauthenticated request hit Symfony's SessionAuthenticator, came
back 401, and the model parked at `ready === false` with an empty
list. Mercure subscribed anonymously (the model explicitly clears the
SSE client's bearer), so subsequent server-side mutations propagated
fine — masking the initial-fetch failure as "list is empty until
something changes". Hit by the second window in examples/todo.

Both classes now implement QQmlParserStatus and trigger the initial
refresh from componentComplete(), where every binding (literal *and*
singleton-derived) is guaranteed to have landed. After completion,
individual setter changes still trigger refresh inline — so token
rotation / URL reassignment after first load behave unchanged.

Regression test under framework/qml/tests/tst_reactive_list_model.qml
using the v0.2.0 qmltestrunner harness. Adds a TestHttpServer helper
that mimics SessionAuthenticator's 401-on-no-bearer behaviour so the
regression is observable; verified the test fails against the unfixed
production code (`Actual: ""` vs `Expected: "Bearer testtoken"` on
the captured Authorization header).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

framework/qml/tests/main.cpp

@@ -4,6 +4,18 @@
 //
 // PLAN.md §13 v0.2.0 testing-strategy row.
 
+#include <QtPlugin>
 #include <QtQuickTest/quicktest.h>
 
+// Static QML modules need their auto-generated plugin classes pulled
+// in explicitly — the linker would otherwise strip the registration
+// init code because nothing in main() references it. Without these
+// imports the QmlEngine that QUICK_TEST_MAIN spins up can't resolve
+// `import PhpQml.Bridge` / `import PhpQml.Bridge.Tests`.
+//
+// Plugin class names are auto-generated by qt_add_qml_module(STATIC)
+// from the URI: dots become underscores, suffixed with "Plugin".
+Q_IMPORT_PLUGIN(PhpQml_BridgePlugin)
+Q_IMPORT_PLUGIN(PhpQml_Bridge_TestsPlugin)
+
 QUICK_TEST_MAIN(qml_unit_tests)