feat: display container images summary on Images tab (#83)

Add a new "Images" tab on the release details page that extracts
and displays all container images (including init containers) from
the release manifest. Images are grouped by image string and show
the associated resource and container name.

Closes #83

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

pkg/dashboard/api.go

@@ -162,6 +162,7 @@ func configureHelms(api *gin.RouterGroup, data *objects.DataLayer) {
 	rels.GET(":ns/:name/history", h.History)
 	rels.GET(":ns/:name/:section", h.GetInfoSection)
 	rels.GET(":ns/:name/resources", h.Resources)
+	rels.GET(":ns/:name/images", h.Images)
 	rels.POST(":ns/:name/rollback", h.Rollback)
 	rels.POST(":ns/:name/test", h.RunTests)