feat(webapp): billing limits — pause, reject, recovery, and settings UI (#3996)

## Summary

Adds Billing Limits to the webapp.

Customers can set a monthly spend cap. When usage crosses the limit,
billable environments enter a grace period. If the limit is not resolved
before grace expires, new triggers are rejected until the organization
increases or removes the limit.

Author: kathiekiwi

.server-changes/billing-limits.md

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+---
+area: webapp
+type: feature
+---
+
+Add billing limits. Customers set a spend cap; when usage crosses it, billable
+environments pause for a grace period, new triggers are rejected once it ends,
+and a recovery flow resumes or cancels the queued backlog. Reconciliation keeps
+the webapp converged to billing's state.
+
+## Manual pause during billing enforcement
+
+While `pauseSource=BILLING_LIMIT`, manual resume is rejected and manual pause is
+a silent no-op (`PauseEnvironmentService` returns success with state `paused`).
+We do not stack a manual pause on top of billing enforcement because resolve
+converge unpauses all `BILLING_LIMIT`-paused environments for the org.
+
+API callers that pause during enforcement should expect the environment to
+resume when the billing limit is resolved. The queues UI hides pause/resume in
+this state; see `manualPauseEnvironmentGuard.server.ts`.
+
+The admin `runs.enable` endpoint skips billing-paused environments when
+re-enabling or disabling org runs (returns them in `skipped`, not `failures` or
+the update count). They resume only after the billing limit is resolved.

apps/webapp/app/components/billing/AnimatedOrgBannerBar.tsx

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+import { ExclamationCircleIcon } from "@heroicons/react/20/solid";
+import { AnimatePresence, motion } from "framer-motion";
+import tileBgPath from "~/assets/images/error-banner-tile@2x.png";
+import { Icon } from "~/components/primitives/Icon";
+import { Paragraph } from "~/components/primitives/Paragraph";
+import { cn } from "~/utils/cn";
+
+type AnimatedOrgBannerBarProps = {
+  show: boolean;
+  variant: "warning" | "error";
+  children: React.ReactNode;
+  action?: React.ReactNode;
+};
+
+export function AnimatedOrgBannerBar({
+  show,
+  variant,
+  children,
+  action,
+}: AnimatedOrgBannerBarProps) {
+  return (
+    <AnimatePresence initial={false}>
+      {show ? (
+        <motion.div
+          className={cn(
+            "flex h-10 items-center justify-between overflow-hidden py-0 pl-3 pr-2",
+            variant === "warning"
+              ? "border-y border-amber-400/20 bg-warning/20"
+              : "border border-error bg-repeat"
+          )}
+          style={
+            variant === "error"
+              ? { backgroundImage: `url(${tileBgPath})`, backgroundSize: "8px 8px" }
+              : undefined
+          }
+          initial={{ opacity: 0, height: 0 }}
+          animate={{ opacity: 1, height: "2.5rem" }}
+          exit={{ opacity: 0, height: 0 }}
+        >
+          <div className="flex items-center gap-2">
+            <Icon
+              icon={ExclamationCircleIcon}
+              className={cn("h-5 w-5", variant === "warning" ? "text-amber-400" : "text-error")}
+            />
+            <Paragraph
+              variant="small"
+              className={variant === "warning" ? "text-amber-200" : "text-error"}
+            >
+              {children}
+            </Paragraph>
+          </div>
+          {action}
+        </motion.div>
+      ) : null}
+    </AnimatePresence>
+  );
+}