feat(gnoweb): disable html in markdown (#2964)

<!-- please provide a detailed description of the changes made in this
pull request. -->

In line with our vision for a HTML-free Gnoweb, this PR disables the
rendering of HTML within Markdown content. It replaces all elements
recognized as HTML tags (e.g., `<div>`, `<br>`, `<web-component>`) with
empty spaces before sending the content to the front-end. The parsing
still happens via JavaScript, but now without any HTML tags. However,
HTML tags like ``` `<div>lorem ipsum</div>` ``` can still appear within
code blocks in Markdown, as usual, but won’t be parsed/read as actual
HTML.

Additionally, this feature is controlled by the `gnoweb` boolean flag
`with-html`, which defaults to `false`.

cc @gfanton 

> [!WARNING] 
> Enabling this feature will break the design of gno.land realms (and
any other realms relying on HTML), since current layout elements like
`columns`, `stacks`, or `jumbotrons`... are built with HTML. We will
need to adopt the new design system expected with `gnoweb2.0` (or future
`gnoweb1` improvements).


### BEFORE:
![127 0 0 1_8888_
(1)](https://github.com/user-attachments/assets/04328db4-7076-4690-9727-50c33f58954d)
### AFTER:
![127 0 0 1_8888_
(2)](https://github.com/user-attachments/assets/b8d9532c-45e6-4a78-b166-2f6d0176bd10)

---
### BEFORE:
![127 0 0
1_8888_r_gnoland_pages](https://github.com/user-attachments/assets/445cbb3f-565b-42af-b794-14f9c682d4ce)
### AFTER:
![127 0 0 1_8888_r_gnoland_pages
(1)](https://github.com/user-attachments/assets/ac7131f1-c2d4-42ea-a426-66244782e910)

---------

Co-authored-by: Manfred Touron <94029+moul@users.noreply.github.com>

contribs/gnodev/go.mod

@@ -1,6 +1,6 @@
 module github.com/gnolang/gno/contribs/gnodev
 
-go 1.22
+go 1.22.0
 
 replace github.com/gnolang/gno => ../..
 

gno.land/cmd/gnoweb/main.go

@@ -37,6 +37,7 @@ func runMain(args []string) error {
 	fs.StringVar(&cfg.HelpRemote, "help-remote", cfg.HelpRemote, "help page's remote addr")
 	fs.BoolVar(&cfg.WithAnalytics, "with-analytics", cfg.WithAnalytics, "enable privacy-first analytics")
 	fs.StringVar(&bindAddress, "bind", "127.0.0.1:8888", "server listening address")
+	fs.BoolVar(&cfg.WithHTML, "with-html", cfg.WithHTML, "Enable HTML parsing in markdown rendering")
 
 	if err := fs.Parse(args); err != nil {
 		return err

gno.land/pkg/gnoweb/gnoweb.go

@@ -13,6 +13,7 @@ import (
 	"net/url"
 	"os"
 	"path/filepath"
+	"regexp"
 	"runtime"
 	"strings"
 	"time"
@@ -45,6 +46,7 @@ type Config struct {
 	HelpChainID   string
 	HelpRemote    string
 	WithAnalytics bool
+	WithHTML      bool
 }
 
 func NewDefaultConfig() Config {
@@ -56,6 +58,7 @@ func NewDefaultConfig() Config {
 		HelpChainID:   "dev",
 		HelpRemote:    "127.0.0.1:26657",
 		WithAnalytics: false,
+		WithHTML:      false,
 	}
 }
 
@@ -109,6 +112,34 @@ func MakeApp(logger *slog.Logger, cfg Config) gotuna.App {
 	return app
 }
 
+var (
+	inlineCodePattern = regexp.MustCompile("`[^`]*`")
+	htmlTagPattern    = regexp.MustCompile(`<\/?\w+[^>]*?>`)
+)
+
+func sanitizeContent(cfg *Config, content string) string {
+	if cfg.WithHTML {
+		return content
+	}
+
+	placeholders := map[string]string{}
+	contentWithPlaceholders := inlineCodePattern.ReplaceAllStringFunc(content, func(match string) string {
+		placeholder := fmt.Sprintf("__GNOMDCODE_%d__", len(placeholders))
+		placeholders[placeholder] = match
+		return placeholder
+	})
+
+	sanitizedContent := htmlTagPattern.ReplaceAllString(contentWithPlaceholders, "")
+
+	if len(placeholders) > 0 {
+		for placeholder, code := range placeholders {
+			sanitizedContent = strings.ReplaceAll(sanitizedContent, placeholder, code)
+		}
+	}
+
+	return sanitizedContent
+}
+
 // handlerRealmAlias is used to render official pages from realms.
 // url is intended to be shorter.
 // UX is intended to be more minimalistic.
@@ -151,7 +182,7 @@ func handlerRealmAlias(logger *slog.Logger, app gotuna.App, cfg *Config, rlmpath
 		tmpl.Set("RealmPath", rlmpath)
 		tmpl.Set("Query", querystr)
 		tmpl.Set("PathLinks", pathLinks)
-		tmpl.Set("Contents", string(res.Data))
+		tmpl.Set("Contents", sanitizeContent(cfg, string(res.Data)))
 		tmpl.Set("Config", cfg)
 		tmpl.Set("IsAlias", true)
 		tmpl.Render(w, r, "realm_render.html", "funcs.html")
@@ -339,7 +370,7 @@ func handleRealmRender(logger *slog.Logger, app gotuna.App, cfg *Config, w http.
 	tmpl.Set("RealmPath", rlmpath)
 	tmpl.Set("Query", querystr)
 	tmpl.Set("PathLinks", pathLinks)
-	tmpl.Set("Contents", string(res.Data))
+	tmpl.Set("Contents", sanitizeContent(cfg, string(res.Data)))
 	tmpl.Set("Config", cfg)
 	tmpl.Set("HasReadme", hasReadme)
 	tmpl.Render(w, r, "realm_render.html", "funcs.html")