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/nav.js

@@ -343,9 +343,23 @@ document.addEventListener("DOMContentLoaded", () => {
     const ul = document.getElementById("stream-list");
     if (!ul) return;
     if (streams.length) {
-      streams.sort();
-      ul.innerHTML = streams.map(uid => `
-        <li><a href="/?profile=${encodeURIComponent(uid)}" class="profile-link">▶ ${uid}</a></li>
+      // Handle both array of UIDs (legacy) and array of stream objects (new)
+      const streamItems = streams.map(item => {
+        if (typeof item === 'string') {
+          // Legacy: array of UIDs
+          return { uid: item, username: item };
+        } else {
+          // New: array of stream objects
+          return {
+            uid: item.uid || '',
+            username: item.username || 'Unknown User'
+          };
+        }
+      });
+      
+      streamItems.sort((a, b) => (a.username || '').localeCompare(b.username || ''));
+      ul.innerHTML = streamItems.map(stream => `
+        <li><a href="/?profile=${encodeURIComponent(stream.uid)}" class="profile-link">▶ ${stream.username}</a></li>
       `).join("");
     } else {
       ul.innerHTML = "<li>No active streams.</li>";