Add NIF previewer plugin with Linux-specific fixes

Vendored from github.com/Parapets/mo2-preview_nif and adapted for Linux:

- BSA texture resolution via MO2 virtual tree with case-insensitive
  fallback walk (Linux FS is case-sensitive; NIFs reference textures
  with arbitrary case against files on disk)
- Process-wide cached BSA candidate list, keyed by profile path,
  priority-sorted, filtering disabled mods
- Path backslash normalization before loose-file lookup
- Polygon offset on SLSF1_Decal-flagged shapes to break z-ties with
  coincident base meshes (road decals, moss overlays)
- Opaque framebuffer via glColorMask alpha lock so alpha-blended shapes
  can't bleed the dialog background through the preview area
- QMouseEvent::globalPosition().toPoint() for Qt6 compatibility

Preview dialog behavior (organizercore.cpp):
- Switch previewFile and previewFileWithAlternatives from stack-allocated
  exec() to heap + ApplicationModal + show() + WA_DeleteOnClose.
- Parent passed as nullptr so preview lifetime is decoupled from the
  stack-allocated ModInfoDialog that spawns it. Nested exec() inside
  the enclosing dialog's exec() was softlocking on close.

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

1 files changed, 37 insertions, 0 deletions

diff --git a/libs/preview_nif/src/Camera.h b/libs/preview_nif/src/Camera.h
new file mode 100644
index 0000000..3d685ea
--- /dev/null
+++ b/libs/preview_nif/src/Camera.h
@@ -0,0 +1,37 @@
+#pragma once
+
+#include <QObject>
+#include <QVector3D>
+
+class Camera : public QObject
+{
+    Q_OBJECT
+
+public:
+    QVector3D lookAt() { return m_LookAt; }
+    float pitch() { return m_Pitch; }
+    float yaw() { return m_Yaw; }
+    float distance() { return m_Distance; }
+
+    void setDistance(float distance);
+    void setLookAt(QVector3D lookAt);
+
+    void pan(QVector3D delta);
+    void rotate(float yaw, float pitch);
+    void zoomDistance(float distance);
+    void zoomFactor(float factor);
+
+private:
+    inline static constexpr float MinDistance = 1.0f;
+    inline static constexpr float MaxDistance = 5000.0f;
+
+    static float repeat(float value, float min, float max);
+
+    QVector3D m_LookAt;
+    float m_Pitch = 0.0f;
+    float m_Yaw = 0.0f;
+    float m_Distance = 100.0f;
+
+signals:
+    void cameraMoved();
+};