feat(ext-vite): replace the web bundler with a Vite extension and its Maven plugin

flash-ext-vite runs Vite's dev server in DEV and otherwise serves the build from the
classpath, read straight from the directory or jar with no manifest. The Maven plugin
flash-ext-vite-maven-plugin builds the frontend at prepare-package and packages it
there, so mvn package makes a jar that serves its own frontend and mvn test needs no
Node. Three overrides remain (root, devPort, basePath); the package manager is read
from the nearest lockfile.

Serving fixes what the bundler got wrong: Vite's hashed files under assets/ are
cached as immutable instead of revalidated, HEAD reports the real Content-Length, a
missing asset is a 404 instead of the index, 304s carry ETag and Cache-Control, and
gzip respects q=0 and is prepared at boot. Every response header is pre-encoded, so
serving allocates nothing, which is what Response.type(byte[]) is for. Vite stops
with the app through onClose, and a lockfile change reinstalls before restarting.

The modes, strategies, logging and command-safety options, the asset-source
abstraction, the manifest and the Jackson dependency are gone: 1,535 lines of main
code become 480, plus 84 for the plugin.

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

flash-extensions/flash-ext-vite/pom.xml

@@ -0,0 +1,34 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>dev.relism</groupId>
+        <artifactId>flash-extensions</artifactId>
+        <version>2.1.0-SNAPSHOT</version>
+    </parent>
+
+    <artifactId>flash-ext-vite</artifactId>
+
+    <dependencies>
+        <dependency>
+            <groupId>dev.relism</groupId>
+            <artifactId>flash</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-api</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>dev.relism</groupId>
+            <artifactId>flash-testing</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+</project>