feat(ext-vite): gzip at build time, fall back to the index only for navigations

The Maven plugin now writes a maximally compressed .gz beside every text file of 1 KB
and more, so the server compresses nothing and boot only reads the files: about 50 ms
for Glossa's 500. Hashed files under assets/ skip the ETag, which nothing ever asks for.

A path that is no file gets index.html only when the request's Accept names text/html,
as a browser navigation does. Everything else, an API call to a missing route included,
gets the app's own 404 instead of the index, and a dot in a client route no longer
matters. The base path itself always serves the app.

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

flash-extensions/flash-ext-vite/src/test/java/dev/relism/flash/ext/vite/AssetsTest.java

@@ -33,7 +33,7 @@ class AssetsTest {
             }
         }
         try (URLClassLoader loader = new URLClassLoader(new URL[]{jar.toUri().toURL()}, null)) {
-            assertEquals(Set.of("/index.html", "/assets/a-12345678.css"), new Assets(loader, "/").byPath.keySet());
+            assertEquals(Set.of("/", "/index.html", "/assets/a-12345678.css"), new Assets(loader, "/").byPath.keySet());
         }
     }
 

flash-extensions/flash-ext-vite/src/test/java/dev/relism/flash/ext/vite/ViteExtensionTest.java

@@ -11,20 +11,14 @@ import static org.junit.jupiter.api.Assertions.assertNull;
 class ViteExtensionTest {
 
     private static final String JS = "/assets/app-AbCd1234.js";
+    private static final String NAVIGATION = "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8";
 
     @RegisterExtension
-    static final FlashTest app = FlashTest.of(flash -> flash.get("/api/before", (req, res) -> "before")
-            .install(new ViteExtension()).get("/api/ping", (req, res) -> "pong"));
+    static final FlashTest app = FlashTest.of(flash -> flash.install(new ViteExtension()));
 
     @RegisterExtension
     static final FlashTest nested = FlashTest.of(flash -> flash.install(new ViteExtension().basePath("/app/")));
 
-    @Test
-    void backendRoutesWin() {
-        app.get("/api/ping").expectStatus(200).expectBody("pong");
-        app.get("/api/before").expectStatus(200).expectBody("before");
-    }
-
     @Test
     void hashedAssetsAreCachedForeverTheRestRevalidates() {
         app.get(JS).expectStatus(200)
@@ -41,17 +35,25 @@ class ViteExtensionTest {
         assertNull(app.get(JS).header("Content-Encoding"));
     }
 
+    /** A browser navigating gets the app, dots and all; a fetch or a script tag for nothing gets a 404. */
     @Test
-    void clientRoutesGetTheIndexMissingFilesA404() {
-        app.get("/content/2").expectStatus(200).expectHeader("Cache-Control", "no-cache").expectBodyContains("spa");
-        app.get("/assets/missing.js").expectStatus(404);
+    void onlyNavigationsFallBackToTheIndex() {
+        for (String route : new String[]{"/content/2", "/users/ada.lovelace"}) {
+            app.request().header("Accept", NAVIGATION).get(route).expectStatus(200).expectHeader("Cache-Control", "no-cache").expectBodyContains("spa");
+        }
+        app.request().header("Accept", "application/json").get("/api/nope").expectStatus(404);
+        app.request().header("Accept", "*/*").get("/assets/missing.js").expectStatus(404);
+        app.get("/content/2").expectStatus(404);
+        app.get("/").expectStatus(200).expectBodyContains("spa");
+        nested.get("/app").expectStatus(200).expectBodyContains("spa");
     }
 
     @Test
-    void anUnchangedAssetIsNotSentAgain() {
-        String etag = app.get(JS).header("ETag");
-        app.request().header("If-None-Match", etag).get(JS).expectStatus(304)
-                .expectHeader("ETag", etag).expectHeader("Cache-Control", "public, max-age=31536000, immutable");
+    void anUnchangedFileIsNotSentAgainAHashedOneIsNeverAsked() {
+        String etag = app.get("/favicon.svg").header("ETag");
+        app.request().header("If-None-Match", etag).get("/favicon.svg").expectStatus(304)
+                .expectHeader("ETag", etag).expectHeader("Cache-Control", "no-cache");
+        assertNull(app.get(JS).header("ETag"));
     }
 
     @Test
@@ -64,7 +66,7 @@ class ViteExtensionTest {
     @Test
     void aBasePathPrefixesEveryRoute() {
         nested.get("/app" + JS).expectStatus(200);
-        nested.get("/app/settings").expectStatus(200).expectBodyContains("spa");
+        nested.request().header("Accept", NAVIGATION).get("/app/settings").expectStatus(200).expectBodyContains("spa");
         nested.get(JS).expectStatus(404);
     }
 }