build: T= aliases ARCH= (board/SBC selection), lock StarForth to fastest

T= is now shorthand for ARCH=, selecting the target board (raspi, amd64,
aarch64, riscv64). StarForth TARGET is locked to fastest — it's the only
build profile. Makefile.starkernel T= wired the same way before ARCH
normalization runs.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Makefile

@@ -3,9 +3,10 @@
 # ==============================================================================
 #
 # Quick Start:
-#   make                          - Standard optimized build (auto ARCH, TARGET=standard)
-#   make TARGET=fastest           - Maximum performance build  (T= is a shorthand: make T=fastest)
-#   make ARCH=arm64 T=fastest     - Build for arm64 (e.g., Raspberry Pi 4)
+#   make                          - Build for host arch (fastest profile, always)
+#   make T=raspi                  - Build for Raspberry Pi 4  (T= is a shorthand for ARCH=)
+#   make T=amd64                  - Build for x86_64
+#   make T=riscv64                - Build for RISC-V 64
 #   make help                     - Show all available targets
 #
 # ==============================================================================
@@ -22,14 +23,13 @@ CC = gcc
 # See docs/DEVELOPER.md for installation instructions
 ISABELLE ?= isabelle
 
-# Architecture / target selection
+# Architecture / target selection — T= is a shorthand for ARCH= (board/SBC)
+ifdef T
+ARCH ?= $(T)
+endif
 ARCH ?= $(shell uname -m)
 ARCH := $(strip $(ARCH))
-TARGET ?= standard
-ifdef T
-TARGET := $(T)
-endif
-TARGET := $(strip $(TARGET))
+TARGET := fastest
 
 # Friendly guardrail: 32-bit builds are not supported
 unsupported_32bit_arches := i386 i486 i586 i686 x86 armv6 armv7 armv7l arm

Makefile.starkernel

@@ -4,10 +4,9 @@
 #
 # Quick start:
 #   make -f Makefile.starkernel                        — build for host arch
-#   make -f Makefile.starkernel ARCH=amd64 qemu        — build + boot (x86_64)
-#   make -f Makefile.starkernel ARCH=aarch64 qemu      — build + boot (aarch64)
-#   make -f Makefile.starkernel ARCH=riscv64 qemu      — build + boot (riscv64)
-#   make -f Makefile.starkernel ARCH=amd64 T=kernel    — T= is a shorthand for TARGET=
+#   make -f Makefile.starkernel T=amd64 qemu           — build + boot (x86_64)   T= is shorthand for ARCH=
+#   make -f Makefile.starkernel T=aarch64 qemu         — build + boot (aarch64)
+#   make -f Makefile.starkernel T=riscv64 qemu         — build + boot (riscv64)
 #   make -f Makefile.starkernel help                   — show all targets
 # ==============================================================================
 
@@ -27,6 +26,10 @@ canon_arch = $(strip \
     $(if $(filter riscv riscv64,$1),riscv64,$1))))))
 
 UNAME_M        := $(shell uname -m)
+# T= is a shorthand for ARCH= (board/SBC selection)
+ifdef T
+ARCH           ?= $(T)
+endif
 ARCH           ?= $(call canon_arch,$(UNAME_M))
 override ARCH  := $(call canon_arch,$(ARCH))
 
@@ -43,11 +46,8 @@ endif
 KCONFIG_ARCH_DIR := $(ARCH)
 include mk/Kconfig.mk
 
-# Target type (default: kernel). T= is a shorthand alias.
+# Target type (default: kernel)
 TARGET    ?= kernel
-ifdef T
-TARGET    := $(T)
-endif
 
 # Kernel-only flags (Phase 6): repointed through the Kconfig bridge, same
 # drop-in-replacement-for-`?=` behavior as every other family in this