Add app detail/info pages with optional config support

- New route: GET /apps/{slug} renders info page with use cases, setup guide, prerequisites
- New API: POST /api/stacks/{name}/optional-config for updating optional env vars
- New structs: AppInfo, OptionalConfigGroup, OptionalConfigField in metadata.go
- UpdateOptionalConfig saves to app.yaml and restarts deployed stacks with new env vars
- Info page template with hero section, screenshots, info cards, optional config form
- Navigation: stack cards now link to /apps/{slug}, deploy page has "Részletek" link

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

controller/internal/web/server.go

@@ -165,6 +165,16 @@ func (s *Server) loadTemplates() {
 			}
 			return r
 		},
+		"screenshotURL": func(slug string, index int) string {
+			return s.cfg.AppScreenshotURL(slug, index)
+		},
+		"seq": func(n int) []int {
+			result := make([]int, n)
+			for i := range result {
+				result[i] = i + 1
+			}
+			return result
+		},
 	}
 
 	s.tmpl = template.Must(template.New("").Funcs(funcMap).Parse(allTemplates))
@@ -475,16 +485,37 @@ func (s *Server) serveAsset(w http.ResponseWriter, r *http.Request, filename str
 	http.ServeFile(w, r, path)
 }
 
-func (s *Server) appDetailHandler(w http.ResponseWriter, r *http.Request, slug string) {
+func (s *Server) appDetailHandler(w http.ResponseWriter, _ *http.Request, slug string) {
+	var found *stacks.Stack
 	for _, stack := range s.stackMgr.GetStacks() {
 		if stack.Meta.Slug == slug {
-			// Always redirect to deploy page — it has a read-only mode for
-			// deployed apps showing current settings, plus the external link
-			http.Redirect(w, r, "/stacks/"+stack.Name+"/deploy", http.StatusFound)
-			return
+			found = &stack
+			break
 		}
 	}
-	http.NotFound(w, r)
+	if found == nil {
+		http.NotFound(w, nil)
+		return
+	}
+
+	// Load current optional config values from app.yaml
+	currentValues := make(map[string]string)
+	if appCfg := s.stackMgr.LoadAppConfigByName(found.Name); appCfg != nil {
+		for k, v := range appCfg.Env {
+			currentValues[k] = v
+		}
+	}
+
+	data := s.baseData("stacks", found.Meta.DisplayName)
+	data["Stack"] = found
+	data["Meta"] = found.Meta
+	data["AppInfo"] = found.Meta.AppInfo
+	data["OptionalConfig"] = found.Meta.OptionalConfig
+	data["CurrentValues"] = currentValues
+	data["HasAppInfo"] = found.Meta.HasAppInfo()
+	data["HasOptionalConfig"] = found.Meta.HasOptionalConfig()
+
+	s.render(w, "app_info", data)
 }
 
 func (s *Server) renderLogin(w http.ResponseWriter, errorMsg string) {