feat(protocol): add route fragment and route registry to schema

- WebUIFragmentRoute proto message (path, fragment_id, exact, name)
- RouteRecord for top-level route registry
- component_templates map for f-template delivery
- Route parser extracting <route> elements from HTML
- Parser plugin: as_any downcasting, generate_f_template dedup
- BTR-to-FAST conversion for <route> to <webui-route>

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: mohamedmansour

crates/webui-handler/src/lib.rs

@@ -193,6 +193,10 @@ impl WebUIHandler {
                         p.on_plugin_data(&plugin_frag.data, context.writer)?;
                     }
                 }
+                Some(Fragment::Route(_)) => {
+                    // Route fragments are handled by the route-aware render path.
+                    // When no route matching is active, route fragments are skipped.
+                }
                 None => {}
             }
         }