feat: implement global error states and toast notifications

[Jayant-kernel]

feat: implement global error states and toast notifications (#125)

This Pull Request fixes #125.

Description

Previously, when the system failed to communicate with the gdbui_server (e.g. backend crash, misconfigured endpoint, initial loading timeouts), Axios errors within data-fetching try/catch blocks were silently swallowed and logged to the console. This resulted in the UI freezing with no user feedback.

This UI enhancement completely solves this developer experience gap by lifting react-toastify into the <App /> root and plumbing toast.error dispatchers directly into all component-level exception handlers.

• Extracted the local <ToastContainer /> from Breakpoint.jsx and mounted it at the global level with proper theme propagation inside App.jsx.

• Replaced the dead console.log(error) fallback logic inside Stack.jsx, Functions.jsx, TerminalComp.jsx, and DataContext.jsx with descriptive, immediate boolean feedback via toast.error("...") alerts.

• ---

Additional context

cc: @charithccmc @Ammoniya for review!

[Jayant-kernel]

This PR implements global error toasts! I elevated <ToastContainer /> to App.jsx and added toast.error() to the exception handlers in Stack, Functions, TerminalComp, and DataContext. Now, if the backend crashes or times out, the user gets a clear red visual alert instead of a frozen UI.

Could you please review and merge? @charithccmc @Ammoniya