feat(ext-web-bundler): add build-time asset scanning and static-frontend strategy

Introduces AssetDirectoryScanner, StaticFrontendStrategy, and WebBundlerBuild for
build-time asset discovery, plus config/docs updates for frontend-type resolution.

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

flash-extensions/flash-ext-web-bundler/docs/frontend-selection.md

@@ -4,7 +4,29 @@ Frontend integration is explicit through `frontendType`.
 
 - No heuristic detection in v1.
 - Deterministic mapping: `FrontendType -> FrontendStrategy`.
-- Current built-in strategy: `VITE`.
+- Built-in strategies: `VITE`, `STATIC`.
+
+## VITE
+
+Orchestrates a dev server process in DEV, serves a prebuilt directory in PROD. See `dev-lifecycle.md`.
+
+## STATIC
+
+For files served as-is — no dev server, no package manager, no build step, no watch loop.
+`STATIC` never orchestrates, in DEV or PROD: it always loads `assetsSource` directly and serves it,
+the same code path `VITE` only uses in PROD. Editing a file during a running dev session requires a
+restart to be picked up (assets are preloaded once, same as `VITE`'s prod serving — no hot reload).
+
+Setting `.frontendType(FrontendType.STATIC)` also switches two other defaults (see `configuration.md`):
+`operationMode` becomes `MANAGED` and `assetsSource` defaults to the `webRoot` itself instead of a
+`dist` subdirectory — a minimal STATIC config is just:
+
+```java
+WebBundlerConfig.builder()
+    .frontendType(FrontendType.STATIC)
+    .webRoot(Path.of("public"))
+    .build()
+```
 
 Extension points: