Add whitemagic-foundation OpenSpec design; isolate reference libs

Design-only foundation for WhiteMagic, a .NET 8 x64 library unifying the
four studied process-manipulation libs. Adds proposal, design (7 decisions),
7 capability specs, and TDD task breakdown; all validate strict.

Move Blackmagic, Blackmagic-old, GreyMagic, MemorySharp, fasm into
reference/ (gitignored) — studied, not built here; each has its own
upstream repo and nested .git. Rewrite plan doc paths to reference/.

Corrects two factual defects found in review:
- current BlackMagic has no D3D EndScene hook; MainThreadPump is net-new
  built on DetourManager, not a port
- no BlackMagic.slnx exists; task 1.3 creates a fresh solution

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,11 @@
+# Reference libraries — studied, not built here (each has its own upstream repo)
+reference/
+
+# .NET build output
+[Bb]in/
+[Oo]bj/
+.vs/
+*.user
+
+# Scratch
+*.tmp