Add mock mode for web UI development and testing

- Add mock data module with simulated camera search and stream discovery
- Enable mock mode via ?mock=true URL parameter
- Show MOCK MODE indicator when enabled
- Remove statistics cards from discovery screen, keep only progress bar
- Mock mode works independently from Go backend for easier UI testing

webui/web/index.html

@@ -207,21 +207,6 @@
                     <p id="progress-text" class="progress-text">Starting scan...</p>
                 </div>
 
-                <div class="stats">
-                    <div class="stat">
-                        <span class="stat-value" id="stat-tested">0</span>
-                        <span class="stat-label">Tested</span>
-                    </div>
-                    <div class="stat">
-                        <span class="stat-value stat-primary" id="stat-found">0</span>
-                        <span class="stat-label">Found</span>
-                    </div>
-                    <div class="stat">
-                        <span class="stat-value" id="stat-remaining">0</span>
-                        <span class="stat-label">Remaining</span>
-                    </div>
-                </div>
-
                 <div id="streams-section" class="streams-section hidden">
                     <h3 class="section-title">Found Connections</h3>