Show Docker images as sub-services under docker service

Agent changes:
- Added get_docker_images() function to list all Docker images
- Use docker images to show stored images with repository:tag and size
- Display images as sub-services under docker service with size in parentheses
- Skip dangling images (<none>:<none>)
- Images shown with active status (always present when listed)

Example display:
● docker                      active     139M     1MB
  ├─ ● docker_gitea           active
  ├─ ○ docker_old-app         inactive
  ├─ ● image_nginx:latest     (142MB)
  ├─ ● image_postgres:15      (379MB)
  └─ ● image_gitea:latest     (256MB)

Updated to version 0.1.174

Cargo.lock

@@ -279,7 +279,7 @@ checksum = "a1d728cc89cf3aee9ff92b05e62b19ee65a02b5702cff7d5a377e32c6ae29d8d"
 
 [[package]]
 name = "cm-dashboard"
-version = "0.1.173"
+version = "0.1.174"
 dependencies = [
  "anyhow",
  "chrono",
@@ -301,7 +301,7 @@ dependencies = [
 
 [[package]]
 name = "cm-dashboard-agent"
-version = "0.1.173"
+version = "0.1.174"
 dependencies = [
  "anyhow",
  "async-trait",
@@ -324,7 +324,7 @@ dependencies = [
 
 [[package]]
 name = "cm-dashboard-shared"
-version = "0.1.173"
+version = "0.1.174"
 dependencies = [
  "chrono",
  "serde",