Fix session persistence after page refresh

Root cause: loadManuallyCreatedProjects() was restoring projects with
stale session arrays from localStorage. When loadProjects() tried to
merge with fresh API data, the stale sessions would override.

Fix 1: In loadManuallyCreatedProjects(), reset the sessions array to
empty for each loaded project. This ensures sessions always come from
the API (authoritative source) rather than localStorage.

Fix 2: In createSessionInFolder(), remove the redundant initialize()
call after loadProjects(). initialize() would reload stale localStorage
data, undoing the fresh data fetched by loadProjects().

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

logs/chat-monitor/failure-1769093185058.json

@@ -0,0 +1,5 @@
+{
+  "sessionId": "session-1769089576431-k4vxmig17",
+  "failureType": "browser_sse_error",
+  "error": "[SSEClient] Connection error for session session-1769092903155-9yow2fvzf: {\"isTrusted\":true}"
+}