Name dinners from links with letter-only words (PR #97 review F2)

Keep only words of at most 20 letters from the link's last path segment,
so punctuated or long token text such as /stew-t=abcdef never reaches
the dinner name, and stop at combined credential words like accesstoken.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/dinners/dinners_test.go

@@ -26,6 +26,10 @@ func TestNameFromURL(t *testing.T) {
 		{"https://example.com/stew-x7k2p9q4", "Stew"},
 		{"https://example.com/recipes/token-abcdefghijk", ""},
 		{"https://example.com/key-lime-pie", "Key lime pie"},
+		{"https://example.com/stew-t=abcdef", "Stew"},
+		{"https://example.com/stew-accesstoken-abcdefghijk", "Stew"},
+		{"https://example.com/stew-abcdefghijklmnopqrstuvwxyz", "Stew"},
+		{"https://example.com/cre%CC%80me-bru%CC%82le%CC%81e", "Cre\u0300me bru\u0302le\u0301e"},
 	}
 	for _, tt := range tests {
 		u, err := url.Parse(tt.link)