fix: InstitutionalReports — signal-aware category filter + Agri/Crypto/Bonds/Indices pills + Specialist Desks link

- Backend: category filter now ORs signal column so multi-category reports (category='multi') appear when filtering by Forex/Energy/Metals/Indices — fixes blank results
- Frontend: category pills expanded to match desk taxonomy (agri, crypto, bonds, indices added; equities kept for compatibility)
- Frontend: banner pointing to /specialist-desks clarifies the split between auto-fetched reports and manual desk report scheduling

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/routers/institutional.py

@@ -114,7 +114,19 @@ def list_reports(
             conditions.append("report_type = ?")
             params.append(report_type)
         if category:
-            conditions.append("category = ?")
+            # For categories that map to a signal column, also match reports
+            # where that signal is non-neutral (most reports have category='multi')
+            _signal_col = {
+                'forex':    'signal_forex',
+                'energy':   'signal_energy',
+                'metals':   'signal_metals',
+                'equities': 'signal_indices',
+                'indices':  'signal_indices',
+            }.get(category)
+            if _signal_col:
+                conditions.append(f"(category = ? OR {_signal_col} != 'neutral')")
+            else:
+                conditions.append("category = ?")
             params.append(category)
         if importance:
             conditions.append("importance >= ?")