Refactor cross-channel tracking and spam detection

Replace per-case trackers with a unified key-based tracker and tighten detection logic. Introduces buildMessageTrackingKeys/collectTrackableText to canonicalize text, extract invite codes, include image fingerprints and dedupe keys; replaces trackCrossChannelMessage/trackImageOnlySpam with trackCrossChannelKeys that tracks multiple normalized keys. Simplifies detectSpam to use trackable content and invite-aware link handling, updates message preview/attachment embedding, and adjusts command/help text to reflect the new "same content across channels" rule. Overall reduces duplicate-prior merging and streamlines cross-channel spam handling.

Anti-Spam/src/rapidSpamTracker.js

@@ -63,15 +63,16 @@ export function trackCrossChannelMessage(guildId, userId, channelId, messageId,
   return trackCrossChannelPost(guildId, userId, channelId, messageId, normalizeKey(text));
 }
 
-export function trackImageOnlySpam(guildId, userId, channelId, messageId, fingerprint) {
-  const trackers = [trackCrossChannelPost(guildId, userId, channelId, messageId, "imgonly")];
-
-  if (fingerprint) {
-    trackers.push(
-      trackCrossChannelPost(guildId, userId, channelId, messageId, `imgfp:${fingerprint}`)
-    );
+export function trackCrossChannelKeys(guildId, userId, channelId, messageId, keys) {
+  const uniqueKeys = [...new Set(keys.map((key) => normalizeKey(key)).filter(Boolean))];
+  if (uniqueKeys.length === 0) {
+    return { duplicateAcrossChannels: false, priorMessages: [] };
   }
 
+  const trackers = uniqueKeys.map((key) =>
+    trackCrossChannelPost(guildId, userId, channelId, messageId, key)
+  );
+
   const duplicateAcrossChannels = trackers.some((tracker) => tracker.duplicateAcrossChannels);
   const priorMessages = duplicateAcrossChannels
     ? dedupePriorMessages(trackers.flatMap((tracker) => tracker.priorMessages))