feat: agent concurrency, conversation summaries, AI tools config, UI polish

- Agent slot limiter for concurrent tool execution
- Conversation summarization with soft-delete (MarkSummarized)
- ANSI stripping in terminal tool output
- Configurable crush-run timeout (default 600s, max 900s)
- Starship theme refactor, AI tools config grid, system update UI
- Streaming segments refactor, summarized messages block in feed
- CSS: headings, scrollbars, tool cards, summary block styles
- i18n additions (en+fr) for tools, updates, config

💘 Generated with Crush

Assisted-by: GLM-5.1 via Crush <crush@charm.land>

internal/api/handlers_missing.go

@@ -226,6 +226,29 @@ func (s *Server) handleSkillsDeploy(w http.ResponseWriter, r *http.Request) {
 	writeJSON(w, map[string]string{"status": "all deployed"})
 }
 
+func (s *Server) handleSkillsUndeploy(w http.ResponseWriter, r *http.Request) {
+	if r.Method != "POST" {
+		writeError(w, "POST only", http.StatusMethodNotAllowed)
+		return
+	}
+	var body struct {
+		Name string `json:"name"`
+	}
+	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
+		writeError(w, err.Error(), http.StatusBadRequest)
+		return
+	}
+	if body.Name == "" {
+		writeError(w, "name is required", http.StatusBadRequest)
+		return
+	}
+	if err := skills.Undeploy(body.Name); err != nil {
+		writeError(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	writeJSON(w, map[string]string{"status": "undeployed", "skill": body.Name})
+}
+
 func (s *Server) handleSSHConnections(w http.ResponseWriter, r *http.Request) {
 	if r.Method != "GET" {
 		writeError(w, "GET only", http.StatusMethodNotAllowed)