Refactor web build process and update documentation

- Removed Node.js build artifacts from .gitignore and adjusted Makefile to reflect changes in web UI build process, now using server-rendered Go templates instead of React.
- Updated README to clarify the new web UI architecture and output formats, emphasizing the removal of the Node.js build step.
- Added a command to set the number of frames per render task in manager configuration, enhancing user control over rendering settings.
- Improved Gitea workflow by removing unnecessary npm install step, streamlining the CI process.

internal/manager/ui_test.go

@@ -0,0 +1,37 @@
+package api
+
+import (
+	"net/http/httptest"
+	"testing"
+)
+
+func TestParseBoolForm(t *testing.T) {
+	req := httptest.NewRequest("POST", "/?flag=true", nil)
+	req.ParseForm()
+	req.Form.Set("enabled", "true")
+	if !parseBoolForm(req, "enabled") {
+		t.Fatalf("expected true for enabled=true")
+	}
+
+	req.Form.Set("enabled", "no")
+	if parseBoolForm(req, "enabled") {
+		t.Fatalf("expected false for enabled=no")
+	}
+}
+
+func TestParseIntQuery(t *testing.T) {
+	req := httptest.NewRequest("GET", "/?limit=42", nil)
+	if got := parseIntQuery(req, "limit", 10); got != 42 {
+		t.Fatalf("expected 42, got %d", got)
+	}
+
+	req = httptest.NewRequest("GET", "/?limit=-1", nil)
+	if got := parseIntQuery(req, "limit", 10); got != 10 {
+		t.Fatalf("expected fallback 10, got %d", got)
+	}
+
+	req = httptest.NewRequest("GET", "/?limit=abc", nil)
+	if got := parseIntQuery(req, "limit", 10); got != 10 {
+		t.Fatalf("expected fallback 10, got %d", got)
+	}
+}