feat: stamp the build version into every service

pkg/version.Version (default "dev") is set at link time via -ldflags from each
service Dockerfile's VERSION build-arg, which the deploy passes as the git tag
(git describe --tags). It surfaces as the OpenTelemetry service.version resource
attribute (so Grafana/Tempo are version-aware), alongside the SPA's existing
About version. Adds the VERSION build-arg to the backend/gateway/validator/bot
compose builds and a serviceResource test covering service.name + service.version.

deploy/docker-compose.yml

@@ -71,6 +71,8 @@ services:
         # Seed dictionary for a FRESH volume; the per-contour value comes from the
         # deploy env (Gitea TEST_/PROD_DICT_VERSION). See the volume note below.
         DICT_VERSION: ${DICT_VERSION:-v1.2.1}
+        # Build version stamped into the binary (git tag; see pkg/version).
+        VERSION: ${APP_VERSION:-dev}
     restart: unless-stopped
     logging: *default-logging
     depends_on:
@@ -132,6 +134,8 @@ services:
         VITE_TELEGRAM_GAME_CHANNEL_NAME: ${VITE_TELEGRAM_GAME_CHANNEL_NAME:-}
         VITE_GATEWAY_URL: ${VITE_GATEWAY_URL:-}
         VITE_APP_VERSION: ${APP_VERSION:-dev}
+        # Go binary version (the SPA's VITE_APP_VERSION is the same git tag).
+        VERSION: ${APP_VERSION:-dev}
     restart: unless-stopped
     logging: *default-logging
     depends_on: [backend]
@@ -218,6 +222,8 @@ services:
       context: ..
       dockerfile: platform/telegram/Dockerfile
       target: validator
+      args:
+        VERSION: ${APP_VERSION:-dev}
     restart: unless-stopped
     logging: *default-logging
     environment:
@@ -268,6 +274,8 @@ services:
       context: ..
       dockerfile: platform/telegram/Dockerfile
       target: bot
+      args:
+        VERSION: ${APP_VERSION:-dev}
     restart: unless-stopped
     logging: *default-logging
     depends_on: [vpn]