feat(rgbd): add RGB-D reconstruction pipeline

Add end-to-end RGB-D reconstruction support across the C++ core and Python API.

- add a native merge_rgbd_views path, view-aware 3D pose containers, and nanobind bindings

- expose Python helpers to sample aligned depth, apply per-joint offsets, lift UVD poses to world space, and run reconstruct_rgbd

- add RGB-D regression tests for merging, manual pipeline parity, symmetric depth sampling windows, and out-of-bounds joints

- bump the project version from 0.1.0 to 0.2.0 for the new feature surface

rpt/CMakeLists.txt

@@ -3,6 +3,7 @@
 set(RPT_SOURCES
     camera.cpp
     interface.cpp
+    rgbd_merger.cpp
     triangulator.cpp
 )