UI/UX redesign: unified refined-glass design system

- Add shared UI primitives: Button, Field/Input/Select, PageHeader,
  Section, Callout, Tabs, Disclosure
- Replace gradient buttons with single blue-accent btn-primary
- Reserve gradient text for the brand wordmark only
- Rework Scanner page onto the glass system; collapse explainer and
  glossary into a disclosure, move filters into a glass toolbar
- Restructure Ticker Detail into tabs (Analysis / Indicators / S/R)
  with chart and recommendation always visible
- Align Watchlist, Rankings, Admin, Login/Register to shared primitives
- Unify stray indigo/violet/gray accents into the blue family

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/src/components/admin/UserTable.tsx

@@ -64,7 +64,7 @@ export function UserTable() {
           Access
         </label>
         <button type="submit" disabled={createUser.isPending || !newUsername.trim() || !newPassword.trim()}
-          className="btn-gradient px-4 py-2 text-sm disabled:opacity-50 disabled:cursor-not-allowed">
+          className="btn-primary px-4 py-2 text-sm disabled:opacity-50 disabled:cursor-not-allowed">
           <span>{createUser.isPending ? 'Creating…' : 'Create User'}</span>
         </button>
       </form>
@@ -103,7 +103,7 @@ export function UserTable() {
                             placeholder="new password" className="w-32 input-glass px-2 py-1 text-xs" />
                           <button onClick={() => handleResetPassword(user.id)}
                             disabled={resetPassword.isPending || !resetPw.trim()}
-                            className="btn-gradient px-2 py-1 text-xs disabled:opacity-50">
+                            className="btn-primary px-2 py-1 text-xs disabled:opacity-50">
                             <span>Save</span>
                           </button>
                           <button onClick={() => { setResetTarget(null); setResetPw(''); }}