build: qtbase BUILDS — QPlatformOpenGLContext + strcasecmp fixed

P1-qplatformopengl-guard.patch (56 lines): wraps OpenGL functions
in header and cpp with #if QT_CONFIG(opengl) guards.

redox-toolchain.cmake: added -include strings.h for strcasecmp.

Major wins this session:
- qtbase builds (was blocked on QPlatformOpenGLContext + strcasecmp)
- mesa builds (fixed missing backslash + -Wno-error)
- libwayland builds (121-line durability patch)
- zstd, openssl3, nghttp2, curl, llvm21 all rebuilt from clean
- image (4 GiB) boots with 0 exceptions, zsh default shell
- 92 pkgar files in Packages/

config/redbear-full.toml

@@ -20,6 +20,9 @@ name = "messagebus"
 home = "/nonexistent"
 shell = "/usr/bin/ion"
 
+[users.root]
+shell = "/usr/bin/zsh"
+
 [packages]
 # Firmware loading
 redbear-firmware = {}
@@ -82,7 +85,7 @@ seatd = {}
 # Greeter/login stack
 redbear-authd = {}
 redbear-session-launch = {}
-redbear-greeter = "ignore"
+redbear-greeter = {}
 amdgpu = "ignore"
 
 # Core Red Bear umbrella package