overhaul WebUI: sub-agent cards, magic effects, UX polish

- Sub-agent rendering: delegate_tasks tool calls render as
  live agent cards with running/complete/error states, file
  lists, token counts, and expandable details
- Magic effects: glowing logo pulse animation, floating
  particle background in empty state, smooth message
  entrance animations, streaming cursor with glow, typing
  indicator dots, status pulse animation
- UX polish: message bubbles with gradient user styling,
  code blocks with copy button, thinking/reasoning toggles,
  full markdown rendering (headers, lists, links, bold, italic,
  strikethrough), session sidebar search, session delete button,
  keyboard shortcuts modal (? key), toast notifications, top
  bar blur backdrop, input gradient send button with hover lift,
  approval dialog styled with risk class colors, session
  refresh on Ctrl+R
- Server: adds DELETE /api/sessions/:id endpoint for session
  deletion from the WebUI

Author: jkyberneees

cmd/kode/serve.go

@@ -84,6 +84,7 @@ Flags:
 	})
 	mux.HandleFunc("/api/resources", handleResourceSearch(resourceReg))
 	mux.HandleFunc("/api/sessions", handleSessionList(store))
+	mux.HandleFunc("/api/sessions/", handleSessionDelete(store))
 
 	listener, err := net.Listen("tcp", addr)
 	if err != nil {
@@ -500,6 +501,29 @@ func handleSessionList(store *session.Store) http.HandlerFunc {
 	}
 }
 
+func handleSessionDelete(store *session.Store) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodDelete {
+			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+			return
+		}
+
+		// Extract session ID from path: /api/sessions/{id}
+		id := strings.TrimPrefix(r.URL.Path, "/api/sessions/")
+		if id == "" {
+			http.Error(w, "missing session id", http.StatusBadRequest)
+			return
+		}
+
+		if err := store.Delete(id); err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+
+		w.WriteHeader(http.StatusNoContent)
+	}
+}
+
 // ── Static Handler ─────────────────────────────────────────────────────
 
 func handleStatic() http.HandlerFunc {