fix(ext-view): clear cross-engine error, propagate globals across JteExtension builder chain

- BaseViewExtension: wrap the ViewRuntimeBridge provider collision with a message
  naming the real constraint (one view engine per FlashApp) instead of the generic
  "duplicate provider" error.
- BaseViewExtension/JteExtension: carry registered globals across JteExtension's
  immutable settings builders (templateRoot/serveStatics/staticPrefix/withStaticCors/
  staticCors). addGlobal() called before any of those used to be silently dropped,
  since each builder method returned a fresh instance with an empty globals list.
- Correct flash-ext-view-jte docs (README, architecture.md, model-and-globals.md):
  globals merge flat with one typed @param per key, not under a global.* namespace
  like Thymeleaf — the docs previously claimed the same reserved namespace for both
  engines, which doesn't match JteRuntime's actual merge behavior.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

flash-extensions/flash-ext-view-jte/src/main/java/dev/relism/flash/ext/view/jte/JteExtension.java

@@ -29,31 +29,32 @@ public final class JteExtension extends BaseViewExtension<JteTarget> {
         this.settings = builder.build();
     }
 
-    private JteExtension(JteSettings settings) {
+    private JteExtension(JteSettings settings, List<GlobalValue> seedGlobals) {
+        super(seedGlobals);
         this.settings = settings;
     }
 
     public JteExtension templateRoot(String templateRoot) {
-        return new JteExtension(settings.toBuilder().templateRoot(templateRoot).build());
+        return new JteExtension(settings.toBuilder().templateRoot(templateRoot).build(), globals());
     }
 
     public JteExtension serveStatics(boolean serveStatics) {
-        return new JteExtension(settings.toBuilder().serveStatics(serveStatics).build());
+        return new JteExtension(settings.toBuilder().serveStatics(serveStatics).build(), globals());
     }
 
     public JteExtension staticPrefix(String staticPrefix) {
-        return new JteExtension(settings.toBuilder().staticPrefix(staticPrefix).build());
+        return new JteExtension(settings.toBuilder().staticPrefix(staticPrefix).build(), globals());
     }
 
     public JteExtension withStaticCors() {
-        return new JteExtension(settings.toBuilder().enableStaticCors(true).build());
+        return new JteExtension(settings.toBuilder().enableStaticCors(true).build(), globals());
     }
 
     public JteExtension staticCors(Consumer<JteSettings.Builder> corsConfig) {
         JteSettings.Builder builder = settings.toBuilder();
         builder.enableStaticCors(true);
         corsConfig.accept(builder);
-        return new JteExtension(builder.build());
+        return new JteExtension(builder.build(), globals());
     }
 
     @Override

flash-extensions/flash-ext-view-jte/src/test/java/dev/relism/flash/ext/view/jte/JteExtensionTest.java

@@ -1,6 +1,11 @@
 package dev.relism.flash.ext.view.jte;
 
+import dev.relism.flash.ext.view.core.RenderedView;
 import dev.relism.flash.ext.view.core.ViewModel;
+import dev.relism.flash.ext.view.core.ViewRuntimeBridge;
+import dev.relism.flash.ext.view.jte.model.HomePage;
+import dev.relism.flash.extension.FlashContext;
+import dev.relism.flash.http.ContentType;
 import dev.relism.flash.models.Request;
 import dev.relism.flash.models.RequestHandler;
 import dev.relism.flash.models.Response;
@@ -89,6 +94,39 @@ class JteExtensionTest {
         assertEquals("https://cdn.example.com", settings.staticCorsAllowOrigin());
     }
 
+    @Test
+    void addGlobal_survives_subsequent_settings_builder_calls() throws Exception {
+        // addGlobal() before a chained settings method (templateRoot/serveStatics/...) used to
+        // be silently dropped: those methods return a *new* JteExtension instance, and the
+        // globals list lived on the instance, not the settings being carried forward.
+        JteExtension ext = new JteExtension(cfg -> cfg.developmentMode(true))
+                .addGlobal("appName", req -> "FlashLab")
+                .templateRoot("templates")
+                .serveStatics(false);
+
+        TestRegistrar app = new TestRegistrar();
+        FlashContext ctx = new FlashContext();
+        ext.configure(app, ctx);
+        ctx.complete();
+
+        @SuppressWarnings("unchecked")
+        ViewRuntimeBridge<JteTarget> runtime = (ViewRuntimeBridge<JteTarget>) ctx.require(ViewRuntimeBridge.class);
+
+        JteHandler handler = new JteHandler() {
+            @Override
+            public ViewModel render(Request req) {
+                return ViewModel.empty()
+                        .with("page", new HomePage("Flash + jte", "elorc"))
+                        .with("build", "dev");
+            }
+        };
+        JteTarget target = new JteTarget("pages/home.jte", ContentType.TEXT_HTML);
+        RenderedView out = runtime.render(handler, target, request("/", null, null, null),
+                new Response(200, ContentType.JSON));
+
+        assertTrue(out.body().contains("FlashLab"), "global registered before templateRoot() must survive");
+    }
+
     @Test
     void routes_register_static_wildcard_when_enabled() {
         JteExtension ext = new JteExtension(cfg -> cfg.staticPrefix("/assets"));