fix(economic): fix national debt panel hang + add lazy pagination (#1928)

- Remove persistCache from nationalDebtBreaker: IndexedDB hydration on
  first call can deadlock in some browsers, causing the panel to hang
  indefinitely showing "Loading debt data from IMF..." with no timeout
- Add 20s hard deadline via Promise.race so loading always resolves
- Extract _fetchNationalDebt() to avoid top-level await in the race
- Lazy-load 20 countries initially with "Load more" button (+20 each tap)
  instead of rendering all 187 rows at once; resets on sort/search change
- Ticker only updates visible rows (not all 187)

src/styles/main.css

@@ -20264,6 +20264,30 @@ body.has-breaking-alert .panels-grid {
   min-width: 70px;
 }
 
+.debt-load-more {
+  width: 100%;
+  padding: 8px;
+  margin: 4px 0;
+  background: none;
+  border: 1px solid var(--border);
+  border-radius: 4px;
+  color: var(--text-dim);
+  font-size: 11px;
+  cursor: pointer;
+  text-align: center;
+  flex-shrink: 0;
+  transition: border-color 0.15s, color 0.15s;
+}
+
+.debt-load-more:hover {
+  border-color: var(--accent);
+  color: var(--accent);
+}
+
+.debt-load-more-count {
+  opacity: 0.6;
+}
+
 .debt-footer {
   display: flex;
   justify-content: space-between;