Add FUSE external mapping support, BG3/Oblivion Remastered fixes, fomod-plus and NaK integration

FUSE VFS now deploys non-data-dir mod mappings (Paks, OBSE, UE4SS, etc.)
via real symlinks and injects file-level data-dir mappings (plugins.txt,
loadorder.txt) into the VFS tree. Fixes game launches for Oblivion
Remastered (Root Builder path resolution, script extender support) and
BG3 (Wine prefix documents directory, file mapper symlinks on Linux).

Vendors mo2-fomod-plus plugin and NaK crate for FOMOD installer and
game finder/runtime support.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

2 files changed, 71 insertions, 0 deletions

diff --git a/libs/installer_fomod_plus/installer/integration/FomodDataContent.cpp b/libs/installer_fomod_plus/installer/integration/FomodDataContent.cpp
new file mode 100644
index 0000000..ac4508d
--- /dev/null
+++ b/libs/installer_fomod_plus/installer/integration/FomodDataContent.cpp
@@ -0,0 +1,50 @@
+#include "FomodDataContent.h"
+
+#include <ifiletree.h>
+
+#include "stringutil.h"
+
+#include <iplugingame.h>
+
+FomodDataContent::FomodDataContent(MOBase::IOrganizer* organizer) : mOrganizer(organizer)
+{
+}
+
+std::vector<MOBase::ModDataContent::Content> FomodDataContent::getAllContents() const
+{
+    static const std::vector<Content> contents = {
+        {FomodDataContentConstants::FOMOD_CONTENT_ID, "FOMOD", ":/fomod/hat", false}
+    };
+
+    return contents;
+}
+
+// Confirmed working, no need to update
+std::vector<int> FomodDataContent::getContentsFor(const std::shared_ptr<const MOBase::IFileTree> fileTree) const
+{
+    std::vector<int> contents;
+    if (!mOrganizer || !fileTree) {
+        return contents;
+    }
+
+    const auto modList = mOrganizer->modList();
+    if (!modList) {
+        return contents;
+    }
+
+    const auto mod = modList->getMod(fileTree->name());
+    if (modHasFomodContent(mod)) {
+       contents.emplace_back(FomodDataContentConstants::FOMOD_CONTENT_ID);
+    }
+    return contents;
+}
+
+bool FomodDataContent::modHasFomodContent(const MOBase::IModInterface* mod)
+{
+    if (!mod) {
+        return false;
+    }
+    const auto pluginName = QString::fromStdString(StringConstants::Plugin::NAME.data());
+    const auto fomodMeta = mod->pluginSetting(pluginName, "fomod", 0);
+    return fomodMeta != 0;
+}
diff --git a/libs/installer_fomod_plus/installer/integration/FomodDataContent.h b/libs/installer_fomod_plus/installer/integration/FomodDataContent.h
new file mode 100644
index 0000000..4ffa3d7
--- /dev/null
+++ b/libs/installer_fomod_plus/installer/integration/FomodDataContent.h
@@ -0,0 +1,21 @@
+#pragma once
+
+#include <imoinfo.h>
+#include <moddatacontent.h>
+
+namespace FomodDataContentConstants {
+constexpr int FOMOD_CONTENT_ID = 400400;
+}
+
+class FomodDataContent final : public MOBase::ModDataContent {
+public:
+    explicit FomodDataContent(MOBase::IOrganizer* organizer);
+
+    [[nodiscard]] std::vector<Content> getAllContents() const override;
+
+    [[nodiscard]] std::vector<int> getContentsFor(std::shared_ptr<const MOBase::IFileTree> fileTree) const override;
+
+private:
+    MOBase::IOrganizer* mOrganizer;
+    static bool modHasFomodContent(const MOBase::IModInterface* mod);
+};