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/rankings/WeightsForm.tsx

@@ -52,7 +52,7 @@ export function WeightsForm({ weights }: WeightsFormProps) {
                 step={1}
                 value={sliderValues[key] ?? 0}
                 onChange={(e) => handleChange(key, e.target.value)}
-                className="h-2 w-full cursor-pointer appearance-none rounded-lg bg-gray-700 accent-indigo-500"
+                className="h-2 w-full cursor-pointer appearance-none rounded-lg bg-gray-700 accent-blue-500"
               />
               <span className="min-w-[2ch] text-right text-sm font-medium text-gray-300">
                 {sliderValues[key] ?? 0}
@@ -69,7 +69,7 @@ export function WeightsForm({ weights }: WeightsFormProps) {
       <button
         type="submit"
         disabled={updateWeights.isPending || allZero}
-        className="mt-4 btn-gradient px-4 py-2 text-sm disabled:opacity-50"
+        className="mt-4 btn-primary px-4 py-2 text-sm disabled:opacity-50"
       >
         <span>{updateWeights.isPending ? 'Updating…' : 'Update Weights'}</span>
       </button>