Add DeepBump normal + height map generator editor tool

Right-click a texture > Process > Generate Normal + Height Map (DeepBump):
runs the DeepBump ML CLI (color_to_normals, then normals_to_height) in the
background with progress display. Sources larger than 2048px are downscaled
via Pillow/Lanczos first (quadratic tile cost, avoids grid seams). Normal
imports as Normal Map, height as linear (sRGB off). Tool lives outside
Assets under Tools/DeepBump (gitignored: cloned repo + local venv).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Assets/Scripts/Editor/TextureNormalMapGenerator.cs.meta

@@ -0,0 +1,2 @@
+fileFormatVersion: 2
+guid: fbe40bb187a4ccc45b2c74267cbc4259