refactor(middleware): replace path prefix checks with function-based approach

Replace simple path prefix-based enforcement/bypass mechanism with a more
flexible function-based approach. This allows for more complex conditions
to determine when middleware should be enforced or bypassed.

- Add checkReqFunc and checkRespFunc types for flexible condition checking
- Replace enforcedPathPrefixes with separate enforce and bypass check functions
- Add static asset path detection for automatic bypassing
- Separate request and response check logic for better granularity

internal/net/gphttp/middleware/bypass_static.go

@@ -0,0 +1,74 @@
+package middleware
+
+import (
+	"net/http"
+
+	"github.com/yusing/godoxy/internal/route/rules"
+)
+
+func must[T any](v T, err error) T {
+	if err != nil {
+		panic(err)
+	}
+	return v
+}
+
+var staticAssetsPaths = map[string]struct{}{
+	// Web app manifests
+	"/manifest.json":        {},
+	"/manifest.webmanifest": {},
+	// Service workers
+	"/sw.js":         {},
+	"/registerSW.js": {},
+	// Favicons
+	"/favicon.ico": {},
+	"/favicon.png": {},
+	"/favicon.svg": {},
+	// Apple icons
+	"/apple-icon.png":                   {},
+	"/apple-touch-icon.png":             {},
+	"/apple-touch-icon-precomposed.png": {},
+	// Microsoft / browser config
+	"/browserconfig.xml": {},
+	// Safari pinned tab
+	"/safari-pinned-tab.svg": {},
+	// Crawlers / SEO
+	"/robots.txt":        {},
+	"/sitemap.xml":       {},
+	"/sitemap_index.xml": {},
+	"/ads.txt":           {},
+}
+
+var staticAssetsGlobs = []rules.Matcher{
+	// Workbox (PWA)
+	must(rules.GlobMatcher("/workbox-window.prod.es5-*.js", false)),
+	must(rules.GlobMatcher("/workbox-*.js", false)),
+	// Favicon variants (e.g. favicon-32x32.png)
+	must(rules.GlobMatcher("/favicon-*.png", false)),
+	// Web app manifest icons
+	must(rules.GlobMatcher("/web-app-manifest-*.png", false)),
+	// Android Chrome icons
+	must(rules.GlobMatcher("/android-chrome-*.png", false)),
+	// Apple touch icon variants
+	must(rules.GlobMatcher("/apple-touch-icon-*.png", false)),
+	// Microsoft tile icons
+	must(rules.GlobMatcher("/mstile-*.png", false)),
+	// Generic PWA / app icons
+	must(rules.GlobMatcher("/pwa-*.png", false)),
+	must(rules.GlobMatcher("/icon-*.png", false)),
+	// Sitemaps (e.g. sitemap-1.xml, sitemap-posts.xml)
+	must(rules.GlobMatcher("/sitemap-*.xml", false)),
+}
+
+func isStaticAssetPath(r *http.Request) bool {
+	if _, ok := staticAssetsPaths[r.URL.Path]; ok {
+		return true
+	}
+
+	for _, matcher := range staticAssetsGlobs {
+		if matcher(r.URL.Path) {
+			return true
+		}
+	}
+	return false
+}