Add geometry database (.rdbview) export to IfcViewerFull

Wire a new "Export Geometry Database" tool button in AddModelDialog,
adjacent to "Convert IFC File to Database", to produce a zipped
read-only artifact combining a lossy RDB (with IfcRepresentationItem
stripped) and a .ifcview geometry sidecar. Intended for cloud
coordination workflows where parametric geometry editing is not needed.

Pipeline changes to support this:

- document_serializer_context gains a `skip_supertypes` field; the
  rdb plugin forwards it to RocksDbSerializer so the same registry
  path produces full or lossy RDBs.

- Vertex quantization helpers (octEncodeNormal + quantizeVertex) move
  out of ViewportWindow.cpp into a shared header so the sidecar's
  byte layout stays identical regardless of whether it came from a
  GPU readback or a CPU pipeline.

- New HeadlessSidecarBuilder runs a GeometryStreamer on the calling
  thread, captures MeshChunk/InstanceChunk into a SidecarData on the
  CPU, then computes georef + packed elements + LODs and writes the
  .ifcview — no ViewportWindow or GL context required.

The Controller's export flow runs RDB conversion + sidecar build +
QZipWriter packaging on a background QThread, writing through
`<dest>.tmp` then renaming for atomic appearance in cloud-sync
folders. ifcviewer-full now links Qt6::CorePrivate for QZipWriter.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/ifcviewer/ViewportWindow.cpp

@@ -20,6 +20,7 @@
 #include "ViewportWindow.h"
 
 #include "AppSettings.h"
+#include "VertexQuantization.h"
 
 #include <QMouseEvent>
 #include <QKeyEvent>
@@ -492,51 +493,6 @@ static GLuint linkProgram(QOpenGLFunctions_4_5_Core* gl, GLuint vert, GLuint fra
 
 // -----------------------------------------------------------------------------
 
-// Meyer et al. octahedral normal encode.  Input unit vector -> [-1,1]^2.
-static void octEncode(const float n[3], float out[2]) {
-    float ax = std::fabs(n[0]), ay = std::fabs(n[1]), az = std::fabs(n[2]);
-    float denom = ax + ay + az;
-    if (denom < 1e-12f) { out[0] = 0.0f; out[1] = 0.0f; return; }
-    float px = n[0] / denom;
-    float py = n[1] / denom;
-    if (n[2] < 0.0f) {
-        float sx = px >= 0.0f ? 1.0f : -1.0f;
-        float sy = py >= 0.0f ? 1.0f : -1.0f;
-        float nx = (1.0f - std::fabs(py)) * sx;
-        float ny = (1.0f - std::fabs(px)) * sy;
-        px = nx; py = ny;
-    }
-    out[0] = px;
-    out[1] = py;
-}
-
-// Quantize a streamer-format vertex (pos3 + normal3 + color-as-float) into
-// the 12 B VBO record, given the mesh's tight local AABB.  `extent_recip`
-// is 1/(max-min) per axis, or 0 for degenerate axes (quantum becomes 0).
-static void quantizeVertex(const float src[7],
-                           const float aabb_min[3],
-                           const float extent_recip[3],
-                           uint8_t dst[INSTANCED_VERTEX_STRIDE_BYTES]) {
-    // Position -> u16 normalized.
-    uint16_t* p = reinterpret_cast<uint16_t*>(dst + INSTANCED_VERTEX_POS_OFFSET);
-    for (int a = 0; a < 3; ++a) {
-        float t = (src[a] - aabb_min[a]) * extent_recip[a];
-        if (t < 0.0f) t = 0.0f; else if (t > 1.0f) t = 1.0f;
-        p[a] = static_cast<uint16_t>(t * 65535.0f + 0.5f);
-    }
-    // Normal -> oct i8x2.  int8 gives ~1.4° worst-case error — fine for BIM.
-    float oct[2];
-    octEncode(src + 3, oct);
-    int8_t* n = reinterpret_cast<int8_t*>(dst + INSTANCED_VERTEX_NORMAL_OFFSET);
-    for (int a = 0; a < 2; ++a) {
-        float v = oct[a];
-        if (v < -1.0f) v = -1.0f; else if (v > 1.0f) v = 1.0f;
-        n[a] = static_cast<int8_t>(std::lrintf(v * 127.0f));
-    }
-    // Color passes through — streamer packs 4 bytes into the 7th float slot.
-    std::memcpy(dst + INSTANCED_VERTEX_COLOR_OFFSET, src + 6, 4);
-}
-
 // Determinant of the upper-left 3x3 of a column-major mat4 stored as 16 floats.
 // Sign tells us whether the transform contains a reflection, which is what
 // decides which glFrontFace winding to draw the instance with.