perf: cap count queries and emit native UUID comparisons for audit/connection logs (#23835)

Audit and connection log pages were timing out due to expensive COUNT(*)
queries over large tables. This commit adds opt-in count capping: requests can
return a `count_cap` field signaling that the count was truncated at a threshold,
avoiding full table scans that caused page timeouts.

Text-cast UUID comparisons in regosql-generated authorization queries
also contributed to the slowdown by preventing index usage for connection
and audit log queries. These now emit native UUID operators.

Frontend changes handle the capped state in usePaginatedQuery and
PaginationWidget, optionally displaying a capped count in the pagination
UI (e.g. "Showing 2,076 to 2,100 of 2,000+ logs")

Related to:
https://linear.app/codercom/issue/PLAT-31/connectionaudit-log-performance-issue

coderd/audit.go

@@ -26,6 +26,11 @@ import (
 	"github.com/coder/coder/v2/codersdk"
 )
 
+// Limit the count query to avoid a slow sequential scan due to joins
+// on a large table. Set to 0 to disable capping (but also see the note
+// in the SQL query).
+const auditLogCountCap = 2000
+
 // @Summary Get audit logs
 // @ID get-audit-logs
 // @Security CoderSessionToken
@@ -66,7 +71,7 @@ func (api *API) auditLogs(rw http.ResponseWriter, r *http.Request) {
 		countFilter.Username = ""
 	}
 
-	// Use the same filters to count the number of audit logs
+	countFilter.CountCap = auditLogCountCap
 	count, err := api.Database.CountAuditLogs(ctx, countFilter)
 	if dbauthz.IsNotAuthorizedError(err) {
 		httpapi.Forbidden(rw)
@@ -81,6 +86,7 @@ func (api *API) auditLogs(rw http.ResponseWriter, r *http.Request) {
 		httpapi.Write(ctx, rw, http.StatusOK, codersdk.AuditLogResponse{
 			AuditLogs: []codersdk.AuditLog{},
 			Count:     0,
+			CountCap:  auditLogCountCap,
 		})
 		return
 	}
@@ -98,6 +104,7 @@ func (api *API) auditLogs(rw http.ResponseWriter, r *http.Request) {
 	httpapi.Write(ctx, rw, http.StatusOK, codersdk.AuditLogResponse{
 		AuditLogs: api.convertAuditLogs(ctx, dblogs),
 		Count:     count,
+		CountCap:  auditLogCountCap,
 	})
 }