Fix project isolation: Make loadChatHistory respect active project sessions

- Modified loadChatHistory() to check for active project before fetching all sessions
- When active project exists, use project.sessions instead of fetching from API
- Added detailed console logging to debug session filtering
- This prevents ALL sessions from appearing in every project's sidebar

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

logs/chat-monitor/failure-1769071986585.json

@@ -0,0 +1,5 @@
+{
+  "sessionId": "session-1769071553847-xz1o05kk9",
+  "failureType": "browser_sse_error",
+  "error": "[SSE] session-output: {\"_eventType\":\"session-output\",\"sessionId\":\"session-1769071553847-xz1o05kk9\",\"type\":\"stdout\",\"content\":\"I'm ready to help! I can create web applications, tools, or any software projects for you. Just tell me what you'd like to build.\\n\\nFor example:\\n- \\\"Create a todo app\\\"\\n- \\\"Build a portfolio website\\\"\\n- \\\"Make a calculator\\\"\\n- \\\"Create a weather dashboard\\\"\\n\\nWhat would you like me to build?\",\"_timestamp\":1769071986041}"
+}