fix: notifications use real data + agent-detail follows new id scheme

1. notification-bell: drop the DEMO_ALERTS fallback (Riya Mehta etc.).
   Empty state ("No active alerts") shows when the live computation
   returns nothing — which is the truthful state until thresholds are
   set on Agent records.
2. use-performance-alerts: bucket calls by c.agentId === agent.id when
   the relation is set; fall back to legacy agentName matching only for
   un-enriched rows. Fixes conversion% calc going to 0 after backfill.
3. agent-table: Link target uses agent.id (UUID or "legacy:NAME") so
   the URL is a stable identifier instead of a display string.
4. agent-detail: parse the route param into UUID vs legacy:NAME, filter
   calls by c.agentId or c.agentName accordingly, and resolve display
   name via the platform Agents list.

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

src/components/dashboard/agent-table.tsx

@@ -95,7 +95,7 @@ export const AgentTable = ({ calls }: AgentTableProps) => {
                     {(agent) => (
                         <Table.Row id={agent.id}>
                             <Table.Cell>
-                                <Link to={`/agent/${encodeURIComponent(agent.name)}`} className="no-underline">
+                                <Link to={`/agent/${encodeURIComponent(agent.id)}`} className="no-underline">
                                     <div className="flex items-center gap-2">
                                         <Avatar size="xs" initials={agent.initials} />
                                         <span className="text-sm font-medium text-brand-secondary hover:text-brand-secondary_hover transition duration-100 ease-linear">{agent.name}</span>