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/gallery_test.go

@@ -0,0 +1,57 @@
+package gallery
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestAlbumFromRel(t *testing.T) {
+	if albumFromRel("portal/IMG_20241012_115041.jpg") != "portal" {
+		t.Fatal("expected portal album")
+	}
+	if albumFromRel("IMG_20241012_115041.jpg") != "" {
+		t.Fatal("expected empty album for root file")
+	}
+}
+
+func TestSafeRelPath(t *testing.T) {
+	if !safeRelPath("portal/foo.jpg") {
+		t.Fatal("valid path rejected")
+	}
+	if safeRelPath("../etc/passwd") {
+		t.Fatal("traversal allowed")
+	}
+}
+
+func TestList_subfolders(t *testing.T) {
+	dir := t.TempDir()
+	album := filepath.Join(dir, "portal")
+	if err := os.MkdirAll(album, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	name := "IMG_20240101_120000.jpg"
+	if err := os.WriteFile(filepath.Join(album, name), []byte("x"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	images, err := List(dir)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(images) != 1 || images[0].Album != "portal" || images[0].RelPath != "portal/"+name {
+		t.Fatalf("got %+v", images)
+	}
+}
+
+func TestCollections_nested(t *testing.T) {
+	images := []Image{
+		{Album: "templeoftechno", CollectionKey: "anniversary", Collection: "Anniversary"},
+		{Album: "templeoftechno", CollectionKey: "groovatory", Collection: "Groovatory"},
+		{Album: "portal", CollectionKey: "x", Collection: "X"},
+	}
+	keys := Collections(images, "templeoftechno")
+	if len(keys) != 2 {
+		t.Fatalf("got %v", keys)
+	}
+}