feat: add useTicketContext hook for PSA ticket context fetching

Accepts psaTicketId and psaConnectionId, fetches context on mount
when both IDs are present, and exposes refresh() for manual re-fetch.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/hooks/useTicketContext.ts

@@ -0,0 +1,40 @@
+import { useState, useEffect, useCallback } from 'react'
+import { psaContextApi, type TicketContext } from '@/api/psaContext'
+
+interface UseTicketContextResult {
+  context: TicketContext | null
+  loading: boolean
+  error: string | null
+  refresh: () => void
+}
+
+export function useTicketContext(
+  psaTicketId: string | null | undefined,
+  psaConnectionId: string | null | undefined
+): UseTicketContextResult {
+  const [context, setContext] = useState<TicketContext | null>(null)
+  const [loading, setLoading] = useState(false)
+  const [error, setError] = useState<string | null>(null)
+
+  const fetchContext = useCallback(async () => {
+    if (!psaTicketId || !psaConnectionId) return
+
+    setLoading(true)
+    setError(null)
+    try {
+      const data = await psaContextApi.getTicketContext(psaTicketId)
+      setContext(data)
+    } catch (err) {
+      const message = err instanceof Error ? err.message : 'Failed to load ticket context'
+      setError(message)
+    } finally {
+      setLoading(false)
+    }
+  }, [psaTicketId, psaConnectionId])
+
+  useEffect(() => {
+    fetchContext()
+  }, [fetchContext])
+
+  return { context, loading, error, refresh: fetchContext }
+}