fix(web): gateway strip's new labels are optional locale keys with an en fallback

`tsc -b` in the Docker image build failed on every non-en locale
(TS2739: gatewayStrip missing degraded, heartbeatStale) because the new
keys were declared required on Translations. The web locales are full
objects, not partial overrides, so a new key must be optional and read
through the `en` fallback — the pattern the existing 102 optional keys
(loadFailed, gateway, gatewayHint, ...) already use.

Before: web `tsc -b` -> 16 x TS2739. After: 0 locale errors.

web/src/components/SidebarStatusStrip.tsx

@@ -2,6 +2,7 @@ import { Link } from "react-router";
 import type { StatusResponse } from "@/lib/api";
 import { cn } from "@/lib/utils";
 import { useI18n } from "@/i18n";
+import { en } from "@/i18n/en";
 
 /** Gateway + session summary for the System sidebar block (no separate strip chrome). */
 export function SidebarStatusStrip({ status }: SidebarStatusStripProps) {
@@ -60,7 +61,7 @@ export function gatewayLine(
     // Live: some channels offline. Retained on a dead PID: a watchdog hard-exited a wedged
     // process (gateway_exit_reason names it) — same verdict `hermes gateway status` prints.
     degraded: {
-      label: g.degraded,
+      label: g.degraded ?? en.app.gatewayStrip.degraded!,
       tone: status.gateway_running ? "text-warning" : "text-destructive",
     },
     stopped: { label: g.stopped, tone: "text-muted-foreground" },
@@ -68,7 +69,7 @@ export function gatewayLine(
   // Alive but housekeeping stopped stamping the heartbeat: 'Running' would be the lie the
   // reporter saw (loop/housekeeping wedged while gateway_state.json still said running).
   if (status.gateway_heartbeat_stale_s != null) {
-    return { label: g.heartbeatStale, tone: "text-destructive" };
+    return { label: g.heartbeatStale ?? en.app.gatewayStrip.heartbeatStale!, tone: "text-destructive" };
   }
   if (status.gateway_state && byState[status.gateway_state]) {
     return byState[status.gateway_state];

web/src/i18n/types.ts

@@ -84,9 +84,9 @@ export interface Translations {
     activeSessionsLabel: string;
     gatewayStatusLabel: string;
     gatewayStrip: {
-      degraded: string;
+      degraded?: string;
       failed: string;
-      heartbeatStale: string;
+      heartbeatStale?: string;
       off: string;
       running: string;
       starting: string;