Build: report per-region memory usage after each build

Pass --print-memory-usage to the linker and re-print its FLASH/RAM/CCMRAM
table in the build-script summary with a computed Free column, so the
headroom for further features is visible at the end of every build.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

build-firmware.sh

@@ -22,14 +22,38 @@ echo "==> Building toolchain image ($IMAGE)"
 docker build --platform linux/amd64 -t "$IMAGE" "$REPO_DIR/docker"
 
 echo "==> Running build in container ($PLATFORM)"
+BUILD_LOG="$(mktemp)"
+trap 'rm -f "$BUILD_LOG"' EXIT
+# Stream to the terminal and capture a copy so we can re-show the linker's
+# memory-usage table at the end (pipefail makes a build failure still abort).
 docker run --rm --platform linux/amd64 \
 	-v "$REPO_DIR":/work \
 	"$IMAGE" \
-	bash /work/docker/build.sh "$PLATFORM"
+	bash /work/docker/build.sh "$PLATFORM" 2>&1 | tee "$BUILD_LOG"
 
 echo
 echo "==> Firmware ready:"
 echo "    $REPO_DIR/MDUV380_firmware/build/${OUT}.bin"
+
+# Re-print the linker's per-region memory usage (emitted by --print-memory-usage
+# during the link) with the free bytes worked out for each region.
+if grep -q "Memory region" "$BUILD_LOG"; then
+	echo
+	echo "==> Memory usage (FLASH = code budget, RAM/CCMRAM = data budget):"
+	grep -A3 "Memory region" "$BUILD_LOG" | awk '
+		function toBytes(n, unit) {
+			if (unit == "KB") return n * 1024
+			if (unit == "MB") return n * 1024 * 1024
+			if (unit == "GB") return n * 1024 * 1024 * 1024
+			return n # already bytes
+		}
+		NR == 1 { printf "    %-9s %11s %12s %8s %11s\n", "Region", "Used", "Size", "Used%", "Free"; next }
+		/:/ {
+			gsub(":", "", $1)
+			used = toBytes($2, $3); size = toBytes($4, $5); free = size - used
+			printf "    %-9s %9d B %10d B %7s %9d B\n", $1, used, size, $6, free
+		}'
+fi
 echo
 echo "Flash it (with the radio in firmware-update mode) using:"
 echo "    ./MDUV380_firmware/tools/opengd77_stm32_firmware_loader.py \\"

docker/firmware.mk

@@ -63,6 +63,7 @@ ASFLAGS := $(CPU) -x assembler-with-cpp -DDEBUG -g3 -MMD -MP
 LDSCRIPT := ../STM32F405VGTX_FLASH.ld
 LDFLAGS := $(CPU) -T$(LDSCRIPT) --specs=nano.specs \
 	-Wl,-Map=$(TARGET).map,--cref -Wl,--gc-sections -static \
+	-Wl,--print-memory-usage \
 	-Wl,--start-group -lc -lm -Wl,--end-group
 
 # ---- Sources --------------------------------------------------------------