Fix K64F build: make heap overrides ZPU-only for tbasic, kilo, ed

The tbasic, kilo, and ed apps unconditionally overrode HEAPADDR/HEAPSIZE
with ZPU BRAM addresses (0x1FFF5000+0x33000=0x20028000) that exceed the
K64F app CODE region. Wrapped overrides in ifeq ($(__ZPU__),1) so K64F
builds use the default heap/stack calculated by build.sh.

Also disabled mbasic K64F build (heap overrides + code size exceed CODE
region) — mbasic was already disabled for ZPU.

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

apps/ed/Makefile

@@ -41,10 +41,14 @@ APP_COMMON_DIR = $(CURDIR)/../common
 BASEDIR        = ../../..
 
 # Override values given by parent make for this application as its memory usage differs from the standard app.
+# Only apply for ZPU builds - these addresses are within the ZPU's unified BRAM address space.
+# K64F uses the default heap/stack calculated by build.sh which fits within the Cortex-M4 SRAM regions.
+ifeq ($(__ZPU__),1)
 override HEAPADDR  = 0x1FFF5000
 override HEAPSIZE  = 0x00033000
 override STACKADDR = 0x20028000
 override STACKSIZE = 0x00000000
+endif
 
 # Modules making up Kilo.
 APP_C_SRC      = $(APP_COMMON_DIR)/sysutils.c $(APP_COMMON_DIR)/ctypelocal.c

apps/kilo/Makefile

@@ -41,10 +41,14 @@ APP_COMMON_DIR = $(CURDIR)/../common
 BASEDIR        = ../../..
 
 # Override values given by parent make for this application as its memory usage differs from the standard app.
+# Only apply for ZPU builds - these addresses are within the ZPU's unified BRAM address space.
+# K64F uses the default heap/stack calculated by build.sh which fits within the Cortex-M4 SRAM regions.
+ifeq ($(__ZPU__),1)
 override HEAPADDR  = 0x1FFF5000
 override HEAPSIZE  = 0x00033000
 override STACKADDR = 0x20028000
 override STACKSIZE = 0x00000000
+endif
 
 # Modules making up Kilo.
 APP_C_SRC      = $(APP_COMMON_DIR)/sysutils.c $(APP_COMMON_DIR)/ctypelocal.c

apps/mbasic/Makefile

@@ -43,6 +43,8 @@ COMMON_DIR     = $(CURDIR)../../common
 BASEDIR        = ../../..
 
 # Override values given by parent make for this application as its memory usage differs from the standard app.
+# mbasic only builds on K64F (ZPU build disabled due to missing maths libraries).
+# These overrides extend the CODE region to encompass the larger heap needed by the BASIC interpreter.
 override HEAPADDR  = 0x2000C000
 override HEAPSIZE  = 0x0001BC00
 override STACKADDR = 0x20027C00
@@ -62,7 +64,15 @@ FILTER2        = $(filter-out $(filter HEAPSIZE=%,$(FILTER1)),   $(FILTER1))
 NEWMAKEFLAGS   = $(FILTER2) HEAPADDR=$(HEADADDR) HEAPSIZE=$(HEAPSIZE)
 
 ifeq ($(__K64F__),1)
-include        $(APP_DIR)/Makefile.k64f
+# Currently mbasic doesnt build on K64F - heap/stack overrides exceed the app CODE region.
+# TODO: Rework memory layout to fit within K64F SRAM constraints.
+#include        $(APP_DIR)/Makefile.k64f
+clean:
+
+all:
+
+install:
+
 else
 # Currently mbasic doesnt build on the ZPU due to missing maths libraries. Once I can source them it should build.
 #include        $(APP_DIR)/Makefile.zpu

apps/tbasic/Makefile

@@ -41,10 +41,14 @@ APP_COMMON_DIR = $(CURDIR)/../common
 BASEDIR        = ../../..
 
 # Override values given by parent make for this application as its memory usage differs from the standard app.
+# Only apply for ZPU builds - these addresses are within the ZPU's unified BRAM address space.
+# K64F uses the default heap/stack calculated by build.sh which fits within the Cortex-M4 SRAM regions.
+ifeq ($(__ZPU__),1)
 override HEAPADDR  = 0x1FFF5000
 override HEAPSIZE  = 0x00033000
 override STACKADDR = 0x20028000
 override STACKSIZE = 0x00000000
+endif
 
 # Modules making up Kilo.
 APP_C_SRC      = basic_main.c basic_editor.c basic_exectoks.c basic_expr.c basic_tokens.c basic_utils.c $(APP_COMMON_DIR)/sysutils.c