fix: update stale cross-links after page consolidation

- BBS boards: cybersecurite→securite, ia→projets (display + nav)
- Base.astro: source comment symbiose→chat

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: ferr079

src/layouts/Base.astro

@@ -45,7 +45,7 @@ const siteUrl = 'https://pixelium.win';
     ║   for the job. Or the right job for the person.           ║
     ║                                                           ║
     ║   → pixelium.win/about                                    ║
-    ║   → pixelium.win/symbiose                                 ║
+    ║   → pixelium.win/chat                                     ║
     ║                                                           ║
     ╚═══════════════════════════════════════════════════════════╝
 

src/pages/bbs.astro

@@ -481,8 +481,8 @@ import Base from '../layouts/Base.astro';
     writeln('  [2]  PROJECTS          pixelium.win/projets', 'amber');
     writeln('  [3]  SECURITY          pixelium.win/securite', 'amber');
     writeln('  [4]  INFRASTRUCTURE    pixelium.win/infrastructure', 'amber');
-    writeln('  [5]  CYBERSECURITY     pixelium.win/cybersecurite', 'amber');
-    writeln('  [6]  AI & AGENTS       pixelium.win/ia', 'amber');
+    writeln('  [5]  CYBERSECURITY     pixelium.win/securite', 'amber');
+    writeln('  [6]  AI & PROJECTS     pixelium.win/projets', 'amber');
     writeln('  [7]  LIVE STATUS       pixelium.win/status', 'amber');
     writeln();
     writeln('  Enter number to open, or /menu to return.', 'dim');
@@ -492,7 +492,7 @@ import Base from '../layouts/Base.astro';
   // Board navigation handler
   const boardUrls: Record<string, string> = {
     '1': '/about', '2': '/projets', '3': '/securite',
-    '4': '/infrastructure', '5': '/cybersecurite', '6': '/ia', '7': '/status',
+    '4': '/infrastructure', '5': '/securite', '6': '/projets', '7': '/status',
   };
 
   // Send chat message