Docs: add nav titles across docs (#5689)

docs/web/control-ui.md

@@ -3,6 +3,7 @@ summary: "Browser-based control UI for the Gateway (chat, nodes, config)"
 read_when:
   - You want to operate the Gateway from a browser
   - You want Tailnet access without SSH tunnels
+title: "Control UI"
 ---
 
 # Control UI (browser)

docs/web/dashboard.md

@@ -2,6 +2,7 @@
 summary: "Gateway dashboard (Control UI) access and auth"
 read_when:
   - Changing dashboard authentication or exposure modes
+title: "Dashboard"
 ---
 
 # Dashboard (Control UI)

docs/web/index.md

@@ -3,6 +3,7 @@ summary: "Gateway web surfaces: Control UI, bind modes, and security"
 read_when:
   - You want to access the Gateway over Tailscale
   - You want the browser Control UI and config editing
+title: "Web"
 ---
 
 # Web (Gateway)

docs/web/webchat.md

@@ -2,6 +2,7 @@
 summary: "Loopback WebChat static host and Gateway WS usage for chat UI"
 read_when:
   - Debugging or configuring WebChat access
+title: "WebChat"
 ---
 
 # WebChat (Gateway WebSocket UI)