Extract webinspect package for logo discovery

Replace the Google Favicons API with HTML head tag parsing
to find higher-quality logos (SVG, apple-touch-icon, large
PNG icons, msapplication-TileImage). The new pkg/webinspect
package parses a website's DOM tree and is extensible for
future resource extraction (footer links, etc.).

Signed-off-by: Émile Ré <emile@getprobo.com>

pkg/webinspect/parse.go

@@ -0,0 +1,110 @@
+// Copyright (c) 2026 Probo Inc <hello@getprobo.com>.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+package webinspect
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+
+	"golang.org/x/net/html"
+)
+
+type PageInfo struct {
+	URL  *url.URL
+	Root *html.Node
+}
+
+func Parse(ctx context.Context, client *http.Client, websiteURL string) (*PageInfo, error) {
+	parsed, err := url.Parse(websiteURL)
+	if err != nil {
+		return nil, fmt.Errorf("cannot parse website URL: %w", err)
+	}
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, websiteURL, nil)
+	if err != nil {
+		return nil, fmt.Errorf("cannot create request: %w", err)
+	}
+
+	resp, err := client.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("cannot fetch page: %w", err)
+	}
+	defer func() { _ = resp.Body.Close() }()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("cannot fetch page: status %d", resp.StatusCode)
+	}
+
+	return ParseHTML(parsed, resp.Body)
+}
+
+func ParseHTML(baseURL *url.URL, r io.Reader) (*PageInfo, error) {
+	root, err := html.Parse(r)
+	if err != nil {
+		return nil, fmt.Errorf("cannot parse HTML: %w", err)
+	}
+
+	return &PageInfo{URL: baseURL, Root: root}, nil
+}
+
+func (p *PageInfo) ResolveHref(href string) string {
+	ref, err := url.Parse(href)
+	if err != nil {
+		return href
+	}
+
+	return p.URL.ResolveReference(ref).String()
+}
+
+func findElement(n *html.Node, tag string) *html.Node {
+	if n.Type == html.ElementNode && n.Data == tag {
+		return n
+	}
+
+	for c := n.FirstChild; c != nil; c = c.NextSibling {
+		if found := findElement(c, tag); found != nil {
+			return found
+		}
+	}
+
+	return nil
+}
+
+func findAllIn(parent *html.Node, tag string) []*html.Node {
+	var nodes []*html.Node
+
+	for c := parent.FirstChild; c != nil; c = c.NextSibling {
+		if c.Type == html.ElementNode && c.Data == tag {
+			nodes = append(nodes, c)
+		}
+
+		nodes = append(nodes, findAllIn(c, tag)...)
+	}
+
+	return nodes
+}
+
+func attrVal(n *html.Node, key string) string {
+	for _, a := range n.Attr {
+		if a.Key == key {
+			return a.Val
+		}
+	}
+
+	return ""
+}