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/gallery/path_test.go

@@ -0,0 +1,22 @@
+package gallery
+
+import "testing"
+
+func TestCollectionFromRel(t *testing.T) {
+	rel := "templeoftechno/Anniversary-20251105T063538Z-1-001/Anniversary/photo.jpg"
+	key, label := collectionFromRel(rel)
+	if label != "Anniversary" {
+		t.Fatalf("label=%q", label)
+	}
+	if key != "anniversary" {
+		t.Fatalf("key=%q", key)
+	}
+}
+
+func TestURLPath_spaces(t *testing.T) {
+	got := URLPath("templeoftechno/The Groovatory/foo.jpg")
+	want := "templeoftechno/The%20Groovatory/foo.jpg"
+	if got != want {
+		t.Fatalf("got %q want %q", got, want)
+	}
+}