Marshal inter-module calls to the owner thread (#79)

* Marshal inter-module calls to the owner thread

Logos inter-module calls go over Qt Remote Objects, whose replicas only
work on the thread that created them (the module's main/event-loop thread).
A module that makes calls from a worker thread — e.g. an embedded HTTP
server serving /metrics — would otherwise hang on replica acquisition.

Make LogosAPIClient transparently marshal to its owner thread when called
off-thread (guarded so same-thread calls run directly with no overhead):
- LogosAPI::getClient creates the client/consumer/replicas on the owner thread
- LogosAPIClient::invokeRemoteMethod / requestObject / onEvent run there too

New header logos_thread_marshal.h (runOnOwnerThread). No new data members —
ABI-safe for statically-linked plugins.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* Add regression test for worker-thread inter-module calls

A provider records the thread its method runs on; a consumer calls it from
a worker thread via LogosAPIClient::invokeRemoteMethod. The call must execute
on the owner (main/event-loop) thread, not the worker thread.

Fails without the marshaling change (the call runs on the worker thread —
0x..d80d0 vs owner 0x..c53e0, "executed on the worker thread instead of the
owner thread"); passes with it (511/511).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* Address review: async marshaling, helper constraints, test ownership

- invokeRemoteMethodAsync now also marshals to the owner thread (non-blocking
  QueuedConnection) — the async path acquires a replica too, so calling it from
  a worker thread previously re-introduced the off-thread bug.
- runOnOwnerThread: document the return-type constraints (void or
  default-constructible, non-reference) and static_assert against references.
- test: declare the provider before its LogosAPI so the ModuleProxy (which
  holds a raw pointer to it) is torn down first — removes the leak and the
  inaccurate comment.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* doctest: call a module from a worker thread (HTTP server)

Adds cpp-sdk-worker-thread-http.test.yaml: builds a sensor_module callee and
an http_module caller that embeds a libmicrohttpd server, runs them in
logoscore, starts the server, and curls it. The HTTP handler calls
sensor_module.readTemperature() from the server's worker thread — which only
works because the SDK marshals the cross-module call onto the module's owner
thread. The module stays pure C++.

Wired into doctests/run.sh and the doctests CI workflow. Validated locally
(23/23 steps pass): `curl` returns `temperature 42`.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

cpp/logos_api.cpp

@@ -1,6 +1,7 @@
 #include "logos_api.h"
 #include "logos_api_client.h"
 #include "logos_api_provider.h"
+#include "logos_thread_marshal.h"
 #include "token_manager.h"
 #include <QVariant>
 #include <string>
@@ -58,6 +59,14 @@ LogosAPIClient* LogosAPI::getClient(const std::string& target_module) const
 LogosAPIClient* LogosAPI::getClient(const QString& target_module,
                                     const LogosTransportConfig& transport) const
 {
+    // Create the client (and its consumers + transport replicas) on this
+    // LogosAPI's owner thread — the module's main/event-loop thread — even when
+    // called from a worker thread (e.g. an HTTP handler). Qt Remote Objects
+    // replicas only work on the thread that created them, so construction (and
+    // the cache it populates) must happen there. invokeRemoteMethod() then
+    // marshals calls back to the same thread. See logos_thread_marshal.h.
+    return logos::runOnOwnerThread(const_cast<LogosAPI*>(this),
+                                   [&]() -> LogosAPIClient* {
     // Single cache, single construction path. Key composition mirrors
     // the factory's resolution rule (see LogosAPIClientCacheKey in
     // logos_api.h):
@@ -90,6 +99,7 @@ LogosAPIClient* LogosAPI::getClient(const QString& target_module,
         const_cast<LogosAPI*>(this));
     m_clients.insert(key, client);
     return client;
+    });
 }
 
 TokenManager* LogosAPI::getTokenManager() const