feat: delete task/account, edit endpoint, richer event log

- store: DeleteAccount, DeleteTask, UpdateEndpoint (+ cascade/update tests)
- httpapi: DELETE /tasks/{id}, DELETE /tasks/{id}/accounts/{accountId},
  PUT /endpoints/{id}; delete guarded with 409 while task running
- orchestrator: enrich WS events with login/host/port/error (test + run + errors)
- web: delete buttons (task, account) with confirm, endpoint edit form,
  human-readable event log (source/dest, host:port, error text)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MMHQTtnQtQqL8muAXHr9kd

internal/httpapi/router.go

@@ -14,10 +14,13 @@ func (s *Server) Router() http.Handler {
 	api := http.NewServeMux()
 	api.HandleFunc("GET /api/endpoints", s.handleListEndpoints)
 	api.HandleFunc("POST /api/endpoints", s.handleCreateEndpoint)
+	api.HandleFunc("PUT /api/endpoints/{id}", s.handleUpdateEndpoint)
 	api.HandleFunc("GET /api/tasks", s.handleListTasks)
 	api.HandleFunc("POST /api/tasks", s.handleCreateTask)
 	api.HandleFunc("GET /api/tasks/{id}", s.handleGetTask)
+	api.HandleFunc("DELETE /api/tasks/{id}", s.handleDeleteTask)
 	api.HandleFunc("POST /api/tasks/{id}/accounts", s.handleCreateAccount)
+	api.HandleFunc("DELETE /api/tasks/{id}/accounts/{accountId}", s.handleDeleteAccount)
 	api.HandleFunc("POST /api/tasks/{id}/import", s.handleImportCSV)
 	api.HandleFunc("POST /api/tasks/{id}/test", s.handleTestAccounts)
 	api.HandleFunc("POST /api/tasks/{id}/run", s.handleRun)