build: derive the project version from VMSIG_VERSION so one tag drives every package + the .so version

CMakeLists.txt

@@ -1,5 +1,8 @@
 cmake_minimum_required(VERSION 3.16)
-project(vmsig VERSION 0.3.4 LANGUAGES C)
+# Single source of truth for the version: CI passes -DVMSIG_VERSION=${TAG#v}, so the project
+# version (-> libvgpu-perception SONAME/.so version) and the .deb version come from one tag.
+set(VMSIG_VERSION "0.3.4" CACHE STRING "Release version (MAJOR.MINOR.PATCH); CI passes the tag")
+project(vmsig VERSION ${VMSIG_VERSION} LANGUAGES C)
 
 set(CMAKE_C_STANDARD 17)
 set(CMAKE_C_STANDARD_REQUIRED ON)

Makefile

@@ -22,7 +22,7 @@ DIST      ?= $(CURDIR)/dist
 # (system / CMAKE_PREFIX_PATH) — the CI path.
 deb:
 	cmake -S . -B $(BUILD_DIR) -DCMAKE_BUILD_TYPE=Release -DVMSIG_INSTALL=ON -DVMSIG_WITH_VMIE=ON \
-	      $(if $(LIBVMIE_PATH),-DLIBVMIE_PATH=$(LIBVMIE_PATH),)
+	      -DVMSIG_VERSION=$(VERSION) $(if $(LIBVMIE_PATH),-DLIBVMIE_PATH=$(LIBVMIE_PATH),)
 	cmake --build $(BUILD_DIR) -j
 	mkdir -p $(DIST)
 	# ---- package: vmsig (component `daemon`) ----