fix(ai): defensive navigation — auto-resolve phantom section IDs to page routes

GPT-4o ignores tool description instructions and sends section:"news"
instead of url:"/news". The client now maintains a whitelist of valid
homepage DOM IDs and a fallback map (news→/news, heritage→/heritage,
parts→/parts). Any section value not in the homepage whitelist gets
auto-resolved to the correct page route via router.push.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/components/ai/SilentObserver.tsx

@@ -78,18 +78,35 @@ export default function SilentObserver() {
         };
         handleClose();
 
-        if (url) {
-          // Mode B: Cross-page navigation
+        // Valid homepage DOM IDs — anything else is a page route
+        const HOMEPAGE_IDS = new Set([
+          "technology", "applications-dashboard", "applications-deep",
+          "global", "our-story", "legacy",
+        ]);
+
+        // Fallback map: if the AI sends a section name that's actually a page
+        const SECTION_TO_PAGE: Record<string, string> = {
+          news: "/news", heritage: "/heritage", parts: "/parts",
+          "parts-catalog": "/parts", contact: "/parts",
+          "inside-flux": "/news", "spare-parts": "/parts",
+        };
+
+        // Resolve: explicit url > section-to-page fallback > homepage scroll
+        const resolvedUrl = url
+          || (section && !HOMEPAGE_IDS.has(section) ? SECTION_TO_PAGE[section] || null : null);
+
+        if (resolvedUrl) {
+          // Cross-page navigation
           setTimeout(() => {
-            router.push(`/${locale}${url}`);
+            router.push(`/${locale}${resolvedUrl}`);
           }, 400);
           addToolOutput({
             tool: "navigate_to_section" as any,
             toolCallId: toolCall.toolCallId,
-            output: `Navigated to page "${url}"`,
+            output: `Navigated to page "${resolvedUrl}"`,
           });
-        } else if (section) {
-          // Mode A: Same-page scroll (existing behavior)
+        } else if (section && HOMEPAGE_IDS.has(section)) {
+          // Same-page scroll — only for confirmed homepage DOM IDs
           setTimeout(() => {
             const el = document.getElementById(section);
             if (el) el.scrollIntoView({ behavior: "smooth", block: "start" });