feat(monkeyd): add /monkeyd_tags to report a novel's tags as hashtags

Replies with a hashtag line led by #MonkeyD, then a blank line and the novel
URL, sent as a code block so it can be copied in one tap. Each genre label
becomes one hashtag with spaces and punctuation stripped and every word
capitalised, since Telegram ends a hashtag at the first character that is not a
letter, digit, or underscore. Diacritics survive; a label with no letters is
dropped rather than emitted as a bare hash.

The command costs one request and runs inline under a short timeout rather than
in the background: handlers are dispatched one at a time, so a stalled fetch
would block every other command. It shares the export page cache.

Advance the submodule to the tag parser, which matches itemprop="genre"
microdata so the site-wide genre navigation stays out of the result.

cmd/server/command_menu_test.go

@@ -68,6 +68,7 @@ func TestCommandDiscovery_AllPublicCommandsHaveSafeMetadata(t *testing.T) {
 		"lol":                  "[date]",
 		"loldle":               "[champion]",
 		"monkeyd_crawl":        "<url> [font_size]",
+		"monkeyd_tags":         "<url>",
 		"random":               "<option,...>",
 		"stats":                "[users | user <username> | cmd <command_name>]",
 		"stock_events":         "<ticker> [days]",