feat: nav counter badges, login backdrop, events i18n + misc fixes

Nav & UI polish
- Sidebar nav items show monospace count badges (projects, sites, stacks,
  proxies). Events badge shows error count only, styled red as actionable
- New $lib/stores/navCounts.ts polls all counts in parallel every 60s and
  refreshes on route change so badges track mutations
- Login page gets a dynamic forge backdrop: rotating conic glow, drifting
  embers, dot-grid texture, vignette — all pure CSS, reduced-motion safe
- main element gets scrollbar-gutter: stable so Settings tab switching no
  longer shifts horizontally when content heights differ

Events i18n
- events.source.* dictionary rewritten to match actually-emitted backend
  sources (deploy, static_site, stale_scanner, stale_cleanup, admin);
  dead keys (container, proxy, system) removed
- EventLogFilter.allSources + /events default sources state updated to match
- Localize "{N} total" via events.totalCount in the page hero toolbar

Backend
- Stage API accepts enable_proxy on create/update (defaults to true) so
  proxy registration can be opted out per stage

Concurrency
- api.ts: queued request waiters no longer double-increment the inflight
  counter; releasing a slot hands it off directly

Reactive effects
- project detail / env / volumes pages wrap side-effect calls in untrack()
  to prevent $effect feedback loops when their loaders mutate tracked state

internal/api/stages.go

@@ -16,6 +16,7 @@ type stageRequest struct {
 	Name            string   `json:"name"`
 	TagPattern      string   `json:"tag_pattern"`
 	AutoDeploy      *bool    `json:"auto_deploy"`
+	EnableProxy     *bool    `json:"enable_proxy"`
 	MaxInstances    *int     `json:"max_instances"`
 	Confirm         *bool    `json:"confirm"`
 	PromoteFrom     string   `json:"promote_from"`
@@ -65,6 +66,10 @@ func (s *Server) createStage(w http.ResponseWriter, r *http.Request) {
 	if req.Confirm != nil {
 		confirm = *req.Confirm
 	}
+	enableProxy := true
+	if req.EnableProxy != nil {
+		enableProxy = *req.EnableProxy
+	}
 
 	var cpuLimit float64
 	if req.CpuLimit != nil {
@@ -80,6 +85,7 @@ func (s *Server) createStage(w http.ResponseWriter, r *http.Request) {
 		Name:            req.Name,
 		TagPattern:      req.TagPattern,
 		AutoDeploy:      autoDeploy,
+		EnableProxy:     enableProxy,
 		MaxInstances:    maxInstances,
 		Confirm:         confirm,
 		PromoteFrom:     req.PromoteFrom,
@@ -135,6 +141,9 @@ func (s *Server) updateStage(w http.ResponseWriter, r *http.Request) {
 	if req.AutoDeploy != nil {
 		updated.AutoDeploy = *req.AutoDeploy
 	}
+	if req.EnableProxy != nil {
+		updated.EnableProxy = *req.EnableProxy
+	}
 	if req.MaxInstances != nil {
 		updated.MaxInstances = *req.MaxInstances
 	}