fix: client perms, @everyone/@channel, docs, unit tests

- usePermissions ORs current user roles + @everyone only (not all server roles)
- cache myRolesByServer; load on active server; refresh after self role edit
- gate/notify @everyone and @channel; plain @username push; special mention UI
- refresh FEATURE_PARITY (DMs exist; drop stale critical gaps)
- README production deploy notes dumpster.service
- unit tests for permission bits and broadcast mention tokens

web/src/components/ChatArea.tsx

@@ -13,7 +13,8 @@ import Picker, { Theme } from 'emoji-picker-react';
 import { CommandDropdown } from "./CommandDropdown";
 import { findCommand, SLASH_COMMANDS } from "../lib/slashCommands";
 import { PollDisplay, CreatePollModal } from "./Poll.tsx";
-import { MentionDropdown } from "./MentionDropdown";
+import { MentionDropdown, buildMentionOptions } from "./MentionDropdown";
+import { usePermissions } from "../lib/usePermissions.ts";
 import { useReadStatesStore } from "../stores/readStates.ts";
 import { MessageSearch } from "./MessageSearch";
 import { ThreadListPanel } from "./ThreadListPanel.tsx";
@@ -45,7 +46,7 @@ function formatTime(iso: string): string {
 }
 
 function renderContent(content: string, memberUsernames: Set<string>) {
-  const segments: { type: "text" | "mention"; value: string }[] = [];
+  const segments: { type: "text" | "mention"; value: string; special?: boolean }[] = [];
   const mentionRe = /@([a-zA-Z0-9_.-]+)/g;
   let last = 0;
   let match: RegExpExecArray | null;
@@ -54,8 +55,13 @@ function renderContent(content: string, memberUsernames: Set<string>) {
       segments.push({ type: "text", value: content.slice(last, match.index) });
     }
     const username = match[1];
-    if (memberUsernames.has(username)) {
-      segments.push({ type: "mention", value: username });
+    const lower = username.toLowerCase();
+    if (lower === "everyone" || lower === "channel" || lower === "here" || memberUsernames.has(username)) {
+      segments.push({
+        type: "mention",
+        value: username,
+        special: lower === "everyone" || lower === "channel" || lower === "here",
+      });
     } else {
       segments.push({ type: "text", value: match[0] });
     }
@@ -71,7 +77,10 @@ function renderContent(content: string, memberUsernames: Set<string>) {
       const nextSeg = segments[idx + 1];
       const needsSpace = !nextSeg || (nextSeg.type === "text" && !nextSeg.value.startsWith(" "));
       return (
-        <span key={idx} className="text-gb-aqua">
+        <span
+          key={idx}
+          className={seg.special ? "text-gb-orange font-bold bg-gb-orange/15 px-0.5 rounded-sm" : "text-gb-aqua"}
+        >
           @{seg.value}{needsSpace ? " " : ""}
         </span>
       );
@@ -329,6 +338,7 @@ export function ChatArea() {
   // Humans only for mentions / nickname lookup (bots live in member list separately).
   const humanMembers = useMemo(() => members.filter((m) => !m.is_bot), [members]);
   const memberUsernames = useMemo(() => new Set(humanMembers.map((m) => m.username)), [humanMembers]);
+  const { canMentionEveryone } = usePermissions(activeServerId);
   const markRead = useReadStatesStore((s) => s.markRead);
   const readStates = useReadStatesStore((s) => s.states);
 
@@ -555,10 +565,7 @@ export function ChatArea() {
       if (!isDropdownOpen) return;
 
       const itemCount = mq !== null
-        ? humanMembers.filter((m) =>
-            m.username.toLowerCase().includes(mq.toLowerCase()) ||
-            m.display_name?.toLowerCase().includes(mq.toLowerCase())
-          ).slice(0, 6).length
+        ? buildMentionOptions(mq, humanMembers, canMentionEveryone).length
         : cq !== null
           ? SLASH_COMMANDS.filter((c) => c.name.startsWith(cq.toLowerCase())).slice(0, 8).length
           : 0;
@@ -575,13 +582,14 @@ export function ChatArea() {
         e.preventDefault();
         e.stopPropagation();
         if (mq !== null) {
-          const q = mq.toLowerCase();
-          const filtered = humanMembers.filter((m) =>
-            m.username.toLowerCase().includes(q) ||
-            m.display_name?.toLowerCase().includes(q)
-          ).slice(0, 6);
-          if (filtered[di]) {
-            handleMentionSelect(filtered[di].username);
+          const options = buildMentionOptions(mq, humanMembers, canMentionEveryone);
+          const selected = options[di];
+          if (selected) {
+            if (selected.kind === "special") {
+              handleMentionSelect(selected.label);
+            } else {
+              handleMentionSelect(selected.member.username);
+            }
           }
         } else if (cq !== null) {
           const q = cq.toLowerCase();
@@ -620,7 +628,7 @@ export function ChatArea() {
     };
     window.addEventListener('keydown', handler);
     return () => window.removeEventListener('keydown', handler);
-  }, [humanMembers, currentUser, activeChannelId, sendMessage, replyToMessage, handleMentionSelect]);
+  }, [humanMembers, canMentionEveryone, currentUser, activeChannelId, sendMessage, replyToMessage, handleMentionSelect]);
 
   const handleSubmit = useCallback(async () => {
     if (mentionQuery !== null || commandQuery !== null) return;
@@ -904,7 +912,13 @@ export function ChatArea() {
               )}
               <div className="p-3 relative">
                 {mentionQuery !== null && (
-                  <MentionDropdown query={mentionQuery} members={humanMembers} selectedIndex={dropdownIndex} onSelect={handleMentionSelect} />
+                  <MentionDropdown
+                    query={mentionQuery}
+                    members={humanMembers}
+                    selectedIndex={dropdownIndex}
+                    onSelect={handleMentionSelect}
+                    canMentionEveryone={canMentionEveryone}
+                  />
                 )}
                 {commandQuery !== null && (
                   <CommandDropdown