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/stacks/deploy.go

@@ -282,6 +282,85 @@ func (m *Manager) GetDeployFields(name string) (*Metadata, *AppConfig, error) {
 	return &meta, appCfg, nil
 }
 
+// UpdateOptionalConfig updates optional env vars in app.yaml and restarts the stack if deployed.
+// Only updates env vars that are listed in the metadata's optional_config sections.
+func (m *Manager) UpdateOptionalConfig(stackName string, values map[string]string) error {
+	stack, ok := m.GetStack(stackName)
+	if !ok {
+		return fmt.Errorf("stack %q not found", stackName)
+	}
+
+	// Build a set of allowed env vars from optional_config
+	allowed := make(map[string]bool)
+	for _, group := range stack.Meta.OptionalConfig {
+		for _, field := range group.Fields {
+			allowed[field.EnvVar] = true
+		}
+	}
+	if len(allowed) == 0 {
+		return fmt.Errorf("no optional config fields defined for %s", stackName)
+	}
+
+	// Load existing app.yaml (or create empty one)
+	stackDir := filepath.Dir(stack.ComposePath)
+	appCfg := LoadAppConfig(stackDir)
+	if appCfg == nil {
+		appCfg = &AppConfig{
+			Env: make(map[string]string),
+		}
+	}
+	if appCfg.Env == nil {
+		appCfg.Env = make(map[string]string)
+	}
+
+	// Update only allowed env vars
+	changed := false
+	for key, val := range values {
+		if !allowed[key] {
+			m.logger.Printf("[WARN] Ignoring non-optional env var: %s", key)
+			continue
+		}
+		if appCfg.Env[key] != val {
+			appCfg.Env[key] = val
+			changed = true
+			m.logger.Printf("[INFO] Updated optional config %s for %s", key, stackName)
+		}
+	}
+
+	if !changed {
+		return nil
+	}
+
+	// Save app.yaml
+	if err := SaveAppConfig(stackDir, appCfg); err != nil {
+		return fmt.Errorf("saving app config: %w", err)
+	}
+	m.logger.Printf("[INFO] Saved updated app.yaml for %s", stackName)
+
+	// If deployed, recreate containers to pick up new env vars
+	// (docker compose restart does NOT pick up new env vars — must use up -d)
+	if stack.Deployed {
+		m.logger.Printf("[INFO] Restarting %s to apply new optional config", stackName)
+		env := m.stackEnv(stackDir)
+		if _, err := m.composeExecCustomEnv(stackDir, env, "up", "-d"); err != nil {
+			return fmt.Errorf("restart after config update: %w", err)
+		}
+		m.logPostStartStatus(stackName, stackDir, env)
+	}
+
+	return m.RefreshStatus()
+}
+
+// LoadAppConfigByName reads app.yaml for a named stack. Returns nil if not found.
+func (m *Manager) LoadAppConfigByName(stackName string) *AppConfig {
+	stack, ok := m.GetStack(stackName)
+	if !ok {
+		return nil
+	}
+	stackDir := filepath.Dir(stack.ComposePath)
+	return LoadAppConfig(stackDir)
+}
+
 // --- App config persistence ---
 
 func LoadAppConfig(stackDir string) *AppConfig {