The editor's rebuildObjects path was destroying every cached model and
re-uploading it on every (debounced) change. Added M2Renderer::clearInstances
that drops only the instance list while keeping models loaded. Editor's
clearObjects switches to clearInstances (M2) + clearInstances (WMO),
and persistent path->modelId maps survive across rebuilds. clearTerrain
fully evicts when loading a new zone.
setGhostPreview reused modelId 59999 for every preview, but loadModel
returns true without doing anything when the ID is already cached. So
selecting a new NPC kept the old ghost model in GPU memory and createInstance
used the stale model. Added M2Renderer::unloadModel public API and call it
from clearGhostPreview.
Re-allocate megaBoneSet_[0..1] in M2Renderer::clear() after vkResetDescriptorPool invalidates all
sets from boneDescPool_. Stale handles were bound to command buffers during rendering, causing
cascading validation errors. Also add ImGui::Dummy() after SetCursorScreenPos in the shaman totem
bar to satisfy ImGui's window boundary extension assertion.
M2Renderer::clear() reset descriptor pools but left the texture cache
and failed-texture tracking intact. On re-login the stale cache filled
the budget, failedTextureRetryAt_ blocked reloads, and the client
entered an infinite model-load loop. Match the cleanup already done in
shutdown() and CharacterRenderer::clear().
