Add Technical Kiwi website with Go, templ, and HTMX.

Single-page site with gallery by album and event, contact form over SMTP,
Docker dev/prod setup, and on-server image derivatives. Gallery photos stay
local (app/images/ is gitignored).

Co-authored-by: Cursor <cursoragent@cursor.com>

app/internal/middleware/middleware.go

@@ -0,0 +1,61 @@
+package middleware
+
+import (
+	"compress/gzip"
+	"io"
+	"net/http"
+	"strconv"
+	"strings"
+	"time"
+)
+
+type gzipResponseWriter struct {
+	http.ResponseWriter
+	io.Writer
+}
+
+func (w *gzipResponseWriter) Write(b []byte) (int, error) {
+	return w.Writer.Write(b)
+}
+
+// Gzip compresses responses when the client accepts it.
+func Gzip(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if !strings.Contains(r.Header.Get("Accept-Encoding"), "gzip") {
+			next.ServeHTTP(w, r)
+			return
+		}
+		w.Header().Set("Vary", "Accept-Encoding")
+		w.Header().Set("Content-Encoding", "gzip")
+		gz := gzip.NewWriter(w)
+		defer gz.Close()
+		next.ServeHTTP(&gzipResponseWriter{ResponseWriter: w, Writer: gz}, r)
+	})
+}
+
+// CacheStatic wraps a file server with long-lived cache headers.
+func CacheStatic(dir string, maxAge time.Duration) http.Handler {
+	fs := http.FileServer(http.Dir(dir))
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Cache-Control", "public, max-age="+formatMaxAge(maxAge)+", immutable")
+		fs.ServeHTTP(w, r)
+	})
+}
+
+// CacheImages wraps image serving; thumbs cache longer than originals.
+func CacheImages(dir string) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		rel := strings.TrimPrefix(r.URL.Path, "/")
+		if strings.HasPrefix(rel, "thumbs/") || strings.HasPrefix(rel, "hero/") {
+			w.Header().Set("Cache-Control", "public, max-age=604800, immutable")
+		} else {
+			w.Header().Set("Cache-Control", "public, max-age=86400")
+		}
+		http.FileServer(http.Dir(dir)).ServeHTTP(w, r)
+	})
+}
+
+func formatMaxAge(d time.Duration) string {
+	return strconv.Itoa(int(d.Seconds()))
+}
+