fix: enable redox-rt proc feature in userutils to fix login crash

userutils compiled redox-rt with default-features=false, disabling the proc feature. This caused login's fork to not pass proc fd to child shell, triggering assertion failed: info.has_proc_fd in redox-rt. P8 patch enables features=['proc']. Verified: zero panics on boot, login works for user/root.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

local/patches/userutils/P8-login-proc-fd.patch

@@ -0,0 +1,7 @@
+diff --git a/Cargo.toml b/Cargo.toml
+index abfc7ae..a05f4fd 100644
+--- a/Cargo.toml
++++ b/Cargo.toml
+@@ -73 +73 @@ ioslice = "0.6"
+-redox-rt = { git = "https://gitlab.redox-os.org/redox-os/relibc", default-features = false }
++redox-rt = { git = "https://gitlab.redox-os.org/redox-os/relibc", default-features = false, features = ["proc"] }

recipes/core/userutils/recipe.toml

@@ -1,6 +1,6 @@
 [source]
 git = "https://gitlab.redox-os.org/redox-os/userutils.git"
-patches = ["P5-redbear-branding.patch", "P6-login-privilege-drop.patch", "P7-login-diagnostics.patch"]
+patches = ["P5-redbear-branding.patch", "P6-login-privilege-drop.patch", "P7-login-diagnostics.patch", "P8-login-proc-fd.patch"]
 
 [build]
 template = "custom"