fix: blank company charts + competitor GUIDs instead of tickers

Trend charts blank:
- trend_windows uses upsert (1 row per ticker/window), so charts had
  at most 1 data point. Added trend_history table (migration 024) that
  appends every snapshot. New /api/trends/history endpoint serves the
  time series. Frontend now uses useTrendHistory for charts and
  useTrends for the latest summary card.

Competitor GUIDs:
- list_competitors query returned raw company_b_id UUIDs without
  joining companies table. Added LEFT JOIN with CASE to resolve the
  other company's ticker and legal_name. Updated Pydantic model to
  include enriched fields. Frontend fallback changed from truncated
  UUID to ticker/legal_name/Unknown.

frontend/src/api/hooks.ts

@@ -236,6 +236,15 @@ export function useTrends(params?: { ticker?: string; window?: string; limit?: n
   return useGet<TrendSummary[]>(['trends', params], 'query', path);
 }
 
+export function useTrendHistory(params?: { ticker?: string; window?: string; limit?: number }) {
+  const qs = new URLSearchParams();
+  if (params?.ticker) qs.set('ticker', params.ticker);
+  if (params?.window) qs.set('window', params.window);
+  if (params?.limit) qs.set('limit', String(params.limit ?? 200));
+  const path = `/api/trends/history${qs.toString() ? '?' + qs : ''}`;
+  return useGet<TrendSummary[]>(['trend-history', params], 'query', path);
+}
+
 export function useTrend(id: string | undefined) {
   return useGet<TrendSummary>(['trend', id], 'query', `/api/trends/${id}`, !!id);
 }

frontend/src/pages/CompanyDetail.tsx

@@ -12,6 +12,7 @@ import {
   useCompetitiveSignals,
   useCorporateDecisions,
   useTrends,
+  useTrendHistory,
 } from '../api/hooks';
 import { StatusBadge, ConfidenceBar, LoadingSpinner, Card } from '../components/ui';
 import { DataTable, type Column } from '../components/DataTable';
@@ -40,6 +41,7 @@ export function CompanyDetailPage() {
   const { data: signals } = useCompetitiveSignals(company?.ticker);
   const { data: decisions } = useCorporateDecisions(company?.ticker);
   const { data: trends } = useTrends({ ticker: company?.ticker, limit: 200 });
+  const { data: trendHistory } = useTrendHistory({ ticker: company?.ticker, limit: 500 });
   const [tab, setTab] = useState<'trends' | 'sources' | 'aliases' | 'macro' | 'competitors' | 'patterns' | 'signals' | 'decisions'>('trends');
 
   if (isLoading || !company) return <LoadingSpinner />;
@@ -78,7 +80,7 @@ export function CompanyDetailPage() {
       </div>
 
       {tab === 'trends' && (
-        <TrendHistoryChart trends={trends ?? []} ticker={company.ticker} />
+        <TrendHistoryChart trends={trendHistory ?? []} latestTrends={trends ?? []} ticker={company.ticker} />
       )}
 
       {tab === 'sources' && (
@@ -360,7 +362,7 @@ function CompetitorsPanel({ competitors, onInfer, isInferring }: {
           {competitors.map((c) => (
             <div key={c.id} className="flex items-center justify-between rounded-lg border border-surface-700 bg-surface-950 p-3">
               <div className="flex items-center gap-3">
-                <span className="font-mono font-semibold text-brand-300">{c.ticker ?? c.company_b_id.slice(0, 8)}</span>
+                <span className="font-mono font-semibold text-brand-300">{c.ticker ?? c.legal_name ?? 'Unknown'}</span>
                 <StatusBadge status={c.relationship_type} />
                 <ConfidenceBar value={c.strength} />
               </div>
@@ -563,10 +565,10 @@ interface ChartPoint {
   window: string;
 }
 
-function TrendHistoryChart({ trends, ticker }: { trends: TrendSummary[]; ticker: string }) {
+function TrendHistoryChart({ trends, latestTrends, ticker }: { trends: TrendSummary[]; latestTrends: TrendSummary[]; ticker: string }) {
   const [selectedWindow, setSelectedWindow] = useState('7d');
 
-  // Filter trends for this ticker and selected window, sorted by time
+  // Use history data for charts
   const filtered = (trends ?? [])
     .filter((t) => t.entity_id === ticker && t.window === selectedWindow)
     .sort((a, b) => new Date(a.generated_at).getTime() - new Date(b.generated_at).getTime());
@@ -582,10 +584,17 @@ function TrendHistoryChart({ trends, ticker }: { trends: TrendSummary[]; ticker:
     window: t.window,
   }));
 
-  // Available windows from the data
-  const availableWindows = [...new Set((trends ?? []).filter((t) => t.entity_id === ticker).map((t) => t.window))];
+  // Available windows from the data (check both history and latest)
+  const allTrends = [...(trends ?? []), ...(latestTrends ?? [])];
+  const availableWindows = [...new Set(allTrends.filter((t) => t.entity_id === ticker).map((t) => t.window))];
   availableWindows.sort((a, b) => WINDOW_ORDER.indexOf(a) - WINDOW_ORDER.indexOf(b));
 
+  // Use latest trends for the summary card
+  const latestForWindow = (latestTrends ?? [])
+    .filter((t) => t.entity_id === ticker && t.window === selectedWindow)
+    .sort((a, b) => new Date(b.generated_at).getTime() - new Date(a.generated_at).getTime());
+  const latest = latestForWindow[0] ?? (filtered.length > 0 ? filtered[filtered.length - 1] : null);
+
   return (
     <div className="space-y-4">
       {/* Window selector */}
@@ -705,8 +714,7 @@ function TrendHistoryChart({ trends, ticker }: { trends: TrendSummary[]; ticker:
           {/* Latest trend summary */}
           <Card>
             <h2 className="mb-3 text-sm font-medium text-gray-400">Latest Trend</h2>
-            {filtered.length > 0 && (() => {
-              const latest = filtered[filtered.length - 1];
+            {latest && (() => {
               return (
                 <dl className="grid grid-cols-2 gap-x-8 gap-y-2 text-sm sm:grid-cols-4">
                   <div>