feat: Improve chat message display

- Add sender name above outgoing messages in group chat
- Display emoji-only messages in larger font size
- Fix leading space before text in quoted replies

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/static/css/style.css

@@ -129,6 +129,13 @@ main {
     color: #6c757d;
 }
 
+.message-footer .message-sender.own {
+    font-weight: 600;
+    font-size: 0.875rem;
+    color: #084298;
+    margin-right: 0.5rem;
+}
+
 /* Message action buttons container */
 .message-actions {
     display: flex;
@@ -680,6 +687,12 @@ main {
     border-left-color: #084298;
 }
 
+/* Large Emoji for emoji-only messages */
+.emoji-large {
+    font-size: 2.5rem;
+    line-height: 1.2;
+}
+
 /* Clickable Links in Messages */
 .message-link {
     color: #0d6efd;

app/static/js/app.js

@@ -728,6 +728,7 @@ function createMessageElement(msg) {
         wrapper.innerHTML = `
             <div class="message-container">
                 <div class="message-footer own">
+                    <span class="message-sender own">${escapeHtml(msg.sender)}</span>
                     <span class="message-time">${time}</span>
                 </div>
                 <div class="message own">

app/static/js/message-utils.js

@@ -11,6 +11,9 @@
 function processMessageContent(content) {
     if (!content) return '';
 
+    // Check if content (minus mentions) is emoji-only BEFORE any processing
+    const emojiOnlyInfo = checkEmojiOnlyContent(content);
+
     // First escape HTML to prevent XSS
     let processed = escapeHtml(content);
 
@@ -27,9 +30,58 @@ function processMessageContent(content) {
     // 4. Convert URLs to links (and images to thumbnails)
     processed = processUrls(processed);
 
+    // 5. If emoji-only, enlarge the emoji
+    if (emojiOnlyInfo.isEmojiOnly) {
+        processed = enlargeEmoji(processed, emojiOnlyInfo.hasMention);
+    }
+
     return processed;
 }
 
+/**
+ * Check if content is emoji-only (excluding @[mentions])
+ * @param {string} text - Raw message content
+ * @returns {object} - { isEmojiOnly: boolean, hasMention: boolean }
+ */
+function checkEmojiOnlyContent(text) {
+    const hasMention = /@\[[^\]]+\]/.test(text);
+
+    // Remove @[...] patterns
+    const withoutMentions = text.replace(/@\[[^\]]+\]/g, '').trim();
+
+    if (!withoutMentions) {
+        return { isEmojiOnly: false, hasMention };
+    }
+
+    // Check if remaining is only emoji (using Unicode Extended_Pictographic)
+    // Matches emoji, modifiers, skin tones, ZWJ sequences, variation selectors, and whitespace
+    const emojiRegex = /^[\p{Extended_Pictographic}\p{Emoji_Modifier}\p{Emoji_Modifier_Base}\p{Emoji_Component}\uFE0F\u200D\s]+$/u;
+    const isEmojiOnly = emojiRegex.test(withoutMentions);
+
+    return { isEmojiOnly, hasMention };
+}
+
+/**
+ * Enlarge emoji in processed HTML
+ * @param {string} html - Processed HTML with mention badges
+ * @param {boolean} hasMention - Whether content has mentions
+ * @returns {string} - HTML with enlarged emoji
+ */
+function enlargeEmoji(html, hasMention) {
+    if (hasMention) {
+        // Add line break after mention badge, then wrap emoji in large class
+        // Pattern: closing </span> of mention badge, optional whitespace, then emoji
+        html = html.replace(
+            /(<\/span>)\s*([\p{Extended_Pictographic}\p{Emoji_Modifier}\p{Emoji_Modifier_Base}\p{Emoji_Component}\uFE0F\u200D\s]+)$/u,
+            '$1<br><span class="emoji-large">$2</span>'
+        );
+    } else {
+        // Just wrap everything in large emoji class
+        html = `<span class="emoji-large">${html}</span>`;
+    }
+    return html;
+}
+
 /**
  * Convert @[Username] mentions to styled badges
  * @param {string} text - HTML-escaped text
@@ -77,8 +129,8 @@ function processChannelLinks(text) {
  * @returns {string} - Text with styled quotes
  */
 function processQuotes(text) {
-    // Match »...« pattern (guillemets)
-    const quotePattern = /»([^«]+)«/g;
+    // Match »...« pattern (guillemets) including optional trailing whitespace
+    const quotePattern = /»([^«]+)«\s*/g;
 
     return text.replace(quotePattern, (_match, quoted) => {
         // Display without guillemets (styling is enough) + line break after