feat(web): add 7 new SEO-optimized pages for organic traffic (#236)

New Pages Added:
- /changelog/ - Release history showing project growth
- /faq/ - SEO-optimized FAQ with JSON-LD schema
- /privacy/ - Privacy policy (trust signal for voice software)
- /shortcuts/ - Keyboard shortcuts and voice commands reference
- /troubleshooting/ - Common issues and solutions
- /use-cases/ - Target audience pages (developers, writers, students, accessibility)
- /alternatives/ - Comparison vs Dragon, Otter.ai, Google Voice Typing

Changes:
- Updated SeoSubpageShell navigation with new pages
- Updated sitemap.xml with all new URLs
- Updated homepage footer with links to new pages
- All pages include proper metadata, JSON-LD schema, and internal linking

SEO Improvements:
- FAQ page with FAQPage schema for rich snippets
- Comparison pages for high-intent keywords
- Use case pages targeting specific audiences
- Privacy page as trust signal for voice software

web/src/components/seo-subpage-shell.tsx

@@ -1,6 +1,6 @@
 import React from "react";
 import Link from "next/link";
-import { BookOpen, ChevronRight, Cpu, Home } from "lucide-react";
+import { BookOpen, ChevronRight, Cpu, HelpCircle, Home, Map, Rss, Shield, Users } from "lucide-react";
 import { VocalinuxLogo } from "@/components/optimized-image";
 
 interface SeoSubpageShellProps {
@@ -23,6 +23,31 @@ const navLinks = [
     label: "Engine Compare",
     icon: Cpu,
   },
+  {
+    href: "/use-cases/",
+    label: "Use Cases",
+    icon: Users,
+  },
+  {
+    href: "/faq/",
+    label: "FAQ",
+    icon: HelpCircle,
+  },
+  {
+    href: "/changelog/",
+    label: "Changelog",
+    icon: Rss,
+  },
+  {
+    href: "/privacy/",
+    label: "Privacy",
+    icon: Shield,
+  },
+  {
+    href: "/alternatives/",
+    label: "Alternatives",
+    icon: Map,
+  },
 ];
 
 export function SeoSubpageShell({ children }: SeoSubpageShellProps) {