Patients page, clinical Settings re-theme, Polar-style user footer

- Patients: new /patients directory table (name, MRN, age·sex, status,
  last seen, allergies) with search + Add patient; clicking a row opens
  the record in the chat via /?patient=<#>. chat-panel reads that search
  param (Suspense-wrapped) and runs the lookup once on arrival. Sidebar
  "Patients" now links to /patients; lib/patients gains listPatients().
- Settings: re-themed to clinical tabs (Profile · Records · Signing ·
  Care team · Developers) — clinician profile, patient notifications,
  patient-owned-storage/signed-records features, and a Signing key panel.
  Same layout/components, only content changed.
- Sidebar footer: Polar-style NavUser (avatar + name + chevron) opening a
  menu upward — Settings · Docs & GitHub · Theme · Log out. Collapsed
  ("locked"): avatar only, name on hover (tooltip), menu opens to the
  right. Placeholder identity (no auth yet).

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

frontend/lib/patients.ts

@@ -261,6 +261,11 @@ const PATIENTS: Record<string, Patient> = {
 
 export const SAMPLE_FILE_NUMBERS = Object.keys(PATIENTS);
 
+// Live list of every patient in the store (includes ones added this session).
+export function listPatients(): Patient[] {
+  return Object.values(PATIENTS);
+}
+
 export async function getPatient(fileNumber: string): Promise<Patient | null> {
   // Simulate retrieval latency so the loading (skeleton) state is visible.
   await new Promise((resolve) => setTimeout(resolve, 700));