fix: add variant diagnostics to health endpoint and lite mode banner

Users running lite mode had no way to tell why AI tools were greyed out.
Now the public health endpoint reports the variant, and a visible banner
appears in the tool panel when running in lite mode.

apps/web/src/components/layout/tool-panel.tsx

@@ -1,4 +1,5 @@
 import { CATEGORIES, TOOLS } from "@stirling-image/shared";
+import { Info } from "lucide-react";
 import { useEffect, useMemo, useState } from "react";
 import { useSettingsStore } from "@/stores/settings-store";
 import { SearchBar } from "../common/search-bar";
@@ -6,7 +7,7 @@ import { ToolCard } from "../common/tool-card";
 
 export function ToolPanel() {
   const [search, setSearch] = useState("");
-  const { disabledTools, experimentalEnabled, variantUnavailableTools, loaded, fetch } =
+  const { variant, disabledTools, experimentalEnabled, variantUnavailableTools, loaded, fetch } =
     useSettingsStore();
 
   useEffect(() => {
@@ -48,6 +49,27 @@ export function ToolPanel() {
         <SearchBar value={search} onChange={setSearch} />
       </div>
       <div className="px-3 pb-4 flex-1">
+        {variant === "lite" && (
+          <div className="mb-3 p-2.5 rounded-lg bg-amber-50 dark:bg-amber-950/30 border border-amber-200 dark:border-amber-800 text-amber-800 dark:text-amber-300">
+            <div className="flex items-start gap-2">
+              <Info className="h-4 w-4 mt-0.5 shrink-0" />
+              <div className="text-xs leading-relaxed">
+                <p className="font-medium">Lite mode</p>
+                <p className="mt-0.5 text-amber-700 dark:text-amber-400">
+                  AI tools are unavailable. Use the{" "}
+                  <code className="font-mono text-[10px] bg-amber-100 dark:bg-amber-900/50 px-1 py-0.5 rounded">
+                    latest
+                  </code>{" "}
+                  or{" "}
+                  <code className="font-mono text-[10px] bg-amber-100 dark:bg-amber-900/50 px-1 py-0.5 rounded">
+                    full
+                  </code>{" "}
+                  tag for all features.
+                </p>
+              </div>
+            </div>
+          </div>
+        )}
         {CATEGORIES.filter((cat) => groupedTools.has(cat.id)).map((category) => (
           <div key={category.id} className="mb-4">
             <h3 className="text-xs font-semibold uppercase text-muted-foreground tracking-wider mb-2">