Add COSS toast notifications and swap in the new logo

Wire COSS's (Base UI) Sonner-style stacked toast into the app:

- Install @coss/toast (components/ui/toast.tsx) and mount <ToastProvider> in
  the root layout; add a small notify.{success,error,info,warning} helper
  (lib/toast.ts) over toastManager so callers don't repeat the toast shape.
- Toast on the events requested: clinic created (onboarding), auth actions
  (sign in / sign up / sign out / password reset request + reset), patient
  saved (create/edit), and all failure branches as error toasts (kept inline
  errors as a fallback). New auth toast strings added to the en translation.
- Replace the logo everywhere: overwrite public/temetro-logo.png with the new
  1024² square mark (same aspect ratio as the old 500², so existing 32×32
  next/image usages stay undistorted; no reference changes needed).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/components/chat/patient-form-dialog.tsx

@@ -30,6 +30,7 @@ import {
   type Patient,
   updatePatient,
 } from "@/lib/patients";
+import { notify } from "@/lib/toast";
 
 type PatientFormDialogProps = {
   open: boolean;
@@ -289,14 +290,17 @@ export function PatientFormDialog({
         : await createPatient(built);
       if (isEdit) {
         onSaved?.(saved);
+        notify.success("Record updated", `${saved.name}'s chart was saved.`);
       } else {
         onCreated?.(saved.fileNumber);
+        notify.success("Patient added", `${saved.name} (${saved.fileNumber}).`);
       }
       onOpenChange(false);
     } catch (err) {
-      setError(
-        err instanceof Error ? err.message : "Could not save the patient.",
-      );
+      const message =
+        err instanceof Error ? err.message : "Could not save the patient.";
+      setError(message);
+      notify.error("Couldn't save patient", message);
     } finally {
       setSubmitting(false);
     }