feat: add agent logs and stats endpoints

- Add GET /api/agents/[id]/logs - conversation activity logs with filtering
- Add GET /api/agents/[id]/stats - aggregated statistics (conversations, tokens, tools)
- Add comprehensive agent endpoint tests (agents.test.ts)
- Fix TypeScript errors in logs route with proper Prisma type inference

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

apps/web/src/app/api/agents/[id]/stats/route.ts

@@ -80,6 +80,7 @@ interface AgentStats {
  * GET /api/agents/[id]/stats
  * Retrieve aggregated statistics for an agent (accepts id or uid)
  */
+// biome-ignore lint/complexity/noExcessiveCognitiveComplexity: Complex aggregation queries needed for stats
 export async function GET(_request: NextRequest, context: RouteContext): Promise<NextResponse> {
   const { id: idOrUid } = await context.params;