feat: migrate UID system from usernames to email addresses

- Database migration: Updated publicstream.uid from usernames to email addresses
  - devuser → oib@bubuit.net
  - oibchello → oib@chello.at
- Updated related tables (UploadLog, UserQuota) to use email-based UIDs
- Fixed backend audio route to map email UIDs to username-based directories
- Updated SSE event payloads to use email for UID and username for display
- Removed redundant display_name field from SSE events
- Fixed frontend rendering conflicts between nav.js and streams-ui.js
- Updated stream player template to display usernames instead of email addresses
- Added cache-busting parameters to force browser refresh
- Created migration script for future reference

Benefits:
- Eliminates UID duplicates and inconsistency
- Provides stable, unique email-based identifiers
- Maintains user-friendly username display
- Follows proper data normalization practices

Fixes: Stream UI now displays usernames (devuser, oibchello) instead of email addresses

static/streams-ui.js

@@ -314,6 +314,7 @@ function loadAndRenderStreams() {
       // Render each stream in sorted order
       streams.forEach((stream, index) => {
         const uid = stream.uid || `stream-${index}`;
+        const username = stream.username || 'Unknown User';
         const sizeMb = stream.size ? (stream.size / (1024 * 1024)).toFixed(1) : '?';
         const mtime = stream.mtime ? new Date(stream.mtime * 1000).toISOString().split('T')[0].replace(/-/g, '/') : '';
         
@@ -323,7 +324,7 @@ function loadAndRenderStreams() {
         try {
           li.innerHTML = `
             <article class="stream-player" data-uid="${escapeHtml(uid)}">
-              <h3>${escapeHtml(uid)}</h3>
+              <h3>${escapeHtml(username)}</h3>
               <div class="audio-controls">
                 <button class="play-pause-btn" data-uid="${escapeHtml(uid)}" aria-label="Play">▶️</button>
               </div>
@@ -397,9 +398,10 @@ export function renderStreamList(streams) {
       ul.innerHTML = streams
         .map(stream => {
           const uid = stream.uid || '';
+          const username = stream.username || 'Unknown User';
           const sizeKb = stream.size ? (stream.size / 1024).toFixed(1) : '?';
           const mtime = stream.mtime ? new Date(stream.mtime * 1000).toLocaleString() : '';
-          return `<li><a href="/?profile=${encodeURIComponent(uid)}" class="profile-link">▶ ${uid}</a> <span style='color:var(--text-muted);font-size:90%'>[${sizeKb} KB, ${mtime}]</span></li>`;
+          return `<li><a href="/?profile=${encodeURIComponent(uid)}" class="profile-link">▶ ${escapeHtml(username)}</a> <span style='color:var(--text-muted);font-size:90%'>[${sizeKb} KB, ${mtime}]</span></li>`;
         })
         .join('');
     } else {