kernel: switch recipe to local fork (path-based source)

Use local/sources/kernel/ as path source instead of git+patches.
The fork is synced to upstream b93260ed and has all Red Bear changes
squash-merged. Old patches preserved in local/patches/kernel/ for
reference only.

Author: vasilito <adminpupkin@gmail.com>

recipes/core/kernel/recipe.toml

@@ -1,30 +1,13 @@
-# Consolidated patch: all Red Bear kernel changes (P0-P10) in a single file.
-# Individual patches preserved in local/patches/kernel/ for reference/rebase.
-# The consolidated patch was generated from applying: redox(no-op), P0-canary,
-# P1-memory-map-overflow, P4-supplementary-groups, P4-s3-suspend-resume,
-# P4-scheme-failure-modes, P5-sched-rt-policy, P5-scheme-sched-id,
-# P5-context-mod-sched, P6-percpu-runqueues, P6-futex-sharding,
-# P8-initial-placement, P9-proc-lock-ordering, P9-numa-topology,
-# P1-boot-path-diagnostics, P10-debug-scheme-serial-fix.
-# Patches that were cumulative supersets (P5-sched-policy-context, P5-proc-setschedpolicy,
-# P5-boot-path-hardening, P6-vruntime-*, P7-cache-affine-*, P7-proc-setname,
-# P7-proc-setpriority, P8-futex-requeue, P8-futex-pi, P8-futex-robust,
-# P8-percpu-wiring, P8-percpu-sched, P8-load-balance, P8-work-stealing,
-# P9-futex-pi-cas-fix) failed to apply at commit 866dfad0 due to
-# context conflicts and are deferred until rebase.
-# P7-scheduler-improvements.patch: removed from recipe patches — 3/4 hunks
-# fail on context.rs at 866dfad0. Rebase needed.
-# P8-msi (applies separately): T1.1 msi.rs (message composition/validation/capability
-# parsing), T1.2 vector.rs (per-CPU bitmatrix allocation), T1.3 IRQ scheme MSI
-# validation gate + iommu hook, T2.2 kernel-side IRQ affinity handler.
+# Kernel is built from the local fork at local/sources/kernel/.
+# The fork is synced to upstream and has all Red Bear changes applied directly.
+# Old patches are preserved in local/patches/kernel/ for reference only.
 [source]
-git = "https://gitlab.redox-os.org/redox-os/kernel.git"
-rev = "866dfad0"
-patches = ["../../../local/patches/kernel/redbear-consolidated.patch", "../../../local/patches/kernel/P8-msi.patch", "../../../local/patches/kernel/P2-rebrand-start-message.patch", "P0-eventfd-kernel.patch", "../../../local/patches/kernel/P1-mkfifo-fifo-support.patch"]
+path = "../../../local/sources/kernel"
 
 [build]
 template = "custom"
 script = """
+export RUSTC_BOOTSTRAP=1
 make -f ${COOKBOOK_SOURCE}/Makefile
 mkdir -pv "${COOKBOOK_STAGE}/usr/lib/boot"
 cp -v kernel "${COOKBOOK_STAGE}/usr/lib/boot"