Clean repo down to what the console image actually uses

- Rewrite README for this fork's purpose (was upstream's multi-image doc)
- Remove 40-CU tooling (files/system, vendor/, docs/, justfiles) — this
  image is deliberately stable-24CU only
- Remove upstream CI (GitHub workflows, release scripts) — builds are
  local, repo lives on Gitea
- Remove unused upstream recipes (deck/kde/gnome × plain/40cu)
- Remove upstream's cosign.pub — we don't sign; keeping their key was
  misleading (verified: recipe generates fine without it, no key baked)
- Update NOTICE: drop removed vendored projects, credit direct upstream

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

NOTICE

@@ -1,15 +1,17 @@
-Bazzite AMD BC-250 Patched Images
-Copyright 2026 FixoLab
+bc250-console
+Derived from "Bazzite AMD BC-250 Patched Images", Copyright 2026 FixoLab.
 
 This repository's original files are licensed under the MIT License unless a
-file or vendored directory states otherwise.
-
-The root LICENSE file applies only to this repository's original files. It does
-not relicense third-party projects, vendored sources, base images, packages, or
+file states otherwise. The root LICENSE file applies only to this repository's
+files. It does not relicense third-party projects, base images, packages, or
 container contents.
 
 This project builds on and/or packages work from the following projects:
 
+- Latest-Bazzite-AMD-BC-250-Patched-Images (direct upstream of this repo)
+  https://github.com/62fixolab/Latest-Bazzite-AMD-BC-250-Patched-Images
+  License: MIT License
+
 - Bazzite
   https://github.com/ublue-os/bazzite
   License: Apache License 2.0
@@ -25,20 +27,6 @@ This project builds on and/or packages work from the following projects:
   License: MIT License
   Note: installed from COPR; not vendored as source in this repository.
 
-- bc250-40cu-unlock
-  https://github.com/duggasco/bc250-40cu-unlock
-  Upstream declared license: GPL-2.0
-  Vendored paths:
-    vendor/bc250-40cu-unlock/
-    files/system/usr/share/bc250-40cu/vendor/bc250-40cu-unlock/
-
-- bc250-cu-live-manager
-  https://github.com/WinnieLV/bc250-cu-live-manager
-  Upstream declared license: none detected at time of review.
-  Vendored paths:
-    vendor/bc250-cu-live-manager/
-    files/system/usr/share/bc250-40cu/vendor/bc250-cu-live-manager/
-
-The experimental 40CU images include third-party research/tooling for BC-250
-runtime CU testing. Those third-party files remain subject to their upstream
-authors' licensing terms and notices.
+The upstream repository's experimental 40-CU tooling (bc250-40cu-unlock,
+bc250-cu-live-manager, and related vendored files) has been removed from this
+fork and is not included in the built image.