docs(credits): add comprehensive CREDITS.md attribution registry

Single attribution registry for every upstream project, dependency,
application, repo, file, and pattern that MiOS is built on top of or
refers to -- with links to each upstream and a short note on its role.

Scope split (intentional, no overlap):
- CREDITS.md  : attribution + origin links (this file)
- LICENSES.md : license terms per component
- SOURCES.md  : KB-grade citation tracking for usr/share/doc/mios
- usr/share/mios/PACKAGES.md : per-RPM accounting

Sections cover: foundational substrate, image-mode atomic stack, base
image lineage, build/sign pipeline, container runtime + Quadlet, local AI
runtime, OpenAI public API spec, AI/LLM tooling, vector RAG datastores,
network/system services, storage + cluster, desktop/graphics, security
stack, GPU stacks, virtualization + VFIO, gaming compat, KB ingestion
conventions, reference distros, MiOS patterns, internal canonical files,
bootstrap repo, and an origin-summary appendix.

No personal/contributor credits yet -- those land when the public
contributor list does.

.gitignore: whitelist /CREDITS.md.

Author: Kabuki94

.gitignore

@@ -29,6 +29,7 @@
 !/AI.md
 !/API.md
 !/CLAUDE.md
+!/CREDITS.md
 !/GEMINI.md
 !/system-prompt.md
 !/ARCHITECTURE.md