Local mode, Makefile, image fixes, Pete avatar

- Add -local flag: web/RSS-only mode that skips Matrix login and posting,
  so the web UI can be exercised against live feeds without credentials
- Add Makefile (build/local/seed/test/clean) that handles Tailwind +
  go build in one shot
- Fix Guardian thumbnails: NormalizeImageURL was rewriting width=1200
  onto signed i.guim.co.uk URLs, invalidating the s= signature and
  returning 401. Leave signed URLs alone and pick the widest
  media:content variant up front instead
- Use pete.avif as the header logo, favicon, and footer mark; drop the
  unused leaf.svg

internal/ingestion/parser.go

@@ -6,10 +6,12 @@ import (
 	"log/slog"
 	"net/http"
 	"regexp"
+	"strconv"
 	"strings"
 	"time"
 
 	"github.com/mmcdole/gofeed"
+	ext "github.com/mmcdole/gofeed/extensions"
 )
 
 const userAgent = "Pete/1.0 (newsbot; +https://github.com/reala-misaki/pete)"
@@ -88,21 +90,19 @@ func extractLede(desc string) string {
 // scraped from content:encoded / description (catches feeds like Ars that
 // embed the lead image in the article body but not as a media:* element).
 func extractImageURL(item *gofeed.Item) string {
-	// Check media content (common in RSS 2.0 with media namespace)
+	// Check media content (common in RSS 2.0 with media namespace).
+	// When multiple media:content variants are advertised (Guardian RSS lists
+	// 140/460/700/1200…) we want the widest signed URL we can find.
 	if item.Extensions != nil {
 		if media, ok := item.Extensions["media"]; ok {
 			if contents, ok := media["content"]; ok {
-				for _, c := range contents {
-					if url := c.Attrs["url"]; url != "" {
-						return url
-					}
+				if url := widestURL(contents); url != "" {
+					return url
 				}
 			}
 			if thumbs, ok := media["thumbnail"]; ok {
-				for _, t := range thumbs {
-					if url := t.Attrs["url"]; url != "" {
-						return url
-					}
+				if url := widestURL(thumbs); url != "" {
+					return url
 				}
 			}
 			// media:group wraps nested media:content / media:thumbnail in some feeds
@@ -143,6 +143,25 @@ func extractImageURL(item *gofeed.Item) string {
 	return ""
 }
 
+// widestURL picks the entry with the largest declared width attribute, falling
+// back to the first URL if none have a parsable width.
+func widestURL(entries []ext.Extension) string {
+	best := ""
+	bestW := -1
+	for _, e := range entries {
+		url := e.Attrs["url"]
+		if url == "" {
+			continue
+		}
+		w, _ := strconv.Atoi(e.Attrs["width"])
+		if w > bestW {
+			best = url
+			bestW = w
+		}
+	}
+	return best
+}
+
 func firstImgSrc(htmlBody string) string {
 	if htmlBody == "" {
 		return ""