fix(maintenance): auto-expiry + adaptive markdown height + tests

- Auto-expiry: expired events auto-end on GET /events via task manager
- Height: _estimate_markdown_height adapted to unit=8px scale with padding detection
- CRITICAL-1: removed dead import remove_chart_from_position (QA finding)
- CRITICAL-2: added chart alive check in ensure_banner_chart (QA finding)
- CRITICAL-3: fixed test assertions update_markdown_chart → update_banner_on_dashboard
- @POST contract: fixed return range [2,12] → [19,200]
- Tests: 8 new tests (auto-expiry + layout height)

build.sh

@@ -225,9 +225,9 @@ bundle_release() {
 
   echo "[bundle] Exporting .tar.xz archives..."
   echo "[bundle] Compressing backend image..."
-  docker save "${backend_tag}" | xz -T0 -9 > "${DIST_ROOT}/backend.${tag}.tar.xz"
+  docker save "${backend_tag}" | xz -T0 -6 > "${DIST_ROOT}/backend.${tag}.tar.xz"
   echo "[bundle] Compressing frontend image..."
-  docker save "${frontend_tag}" | xz -T0 -9 > "${DIST_ROOT}/frontend.${tag}.tar.xz"
+  docker save "${frontend_tag}" | xz -T0 -6 > "${DIST_ROOT}/frontend.${tag}.tar.xz"
 
   echo "[bundle] Calculating checksums..."
   (
@@ -269,10 +269,7 @@ services:
     ports:
       - "\${BACKEND_HOST_PORT:-8001}:8000"
     volumes:
-      - ./config.json:/app/config.json:ro
-      - ./backups:/app/backups
-      - ./backend/git_repos:/app/backend/git_repos
-      - \${STORAGE_ROOT:-./storage}:/app/storage
+      - ./storage:/app/storage
       - \${CERTS_PATH:-./certs}:/opt/certs:ro
 
   frontend:
@@ -369,7 +366,7 @@ bundle_light() {
   docker build -f docker/all-in-one.Dockerfile -t "${image_tag}" .
 
   echo "[bundle:light] Exporting .tar.xz..."
-  docker save "${image_tag}" | xz -T0 -9 > "${DIST_ROOT}/ss-tools.${tag}.tar.xz"
+  docker save "${image_tag}" | xz -T0 -6 > "${DIST_ROOT}/ss-tools.${tag}.tar.xz"
 
   echo "[bundle:light] Calculating checksums..."
   (
@@ -446,10 +443,7 @@ services:
     ports:
       - "${APP_HOST_PORT:-8000}:8000"
     volumes:
-      - ./config.json:/app/config.json:ro
-      - ./backups:/app/backups
-      - ./backend/git_repos:/app/backend/git_repos
-      - ${STORAGE_ROOT:-./storage}:/app/storage
+      - ./storage:/app/storage
 
 volumes:
   postgres_data: