fix: preserve project name casing in group headers (#158)

## Summary

- Remove `text-transform: capitalize` from `.group-header` so project
names display with their original casing from the filesystem
- Revert the `notifySyncComplete()` suppression during session watches —
it caused stale sidebar and filter state (projects, agents, session
counts stopped updating while any session was selected)

## Test plan

- [ ] Open a session with "Group by project" enabled — project names
should show original casing (e.g. "myProject" not "Myproject")
- [ ] While watching a live session, trigger a background sync — sidebar
session list and filter dropdowns should update without going stale

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
Co-authored-by: Wes McKinney <wesmckinn+git@gmail.com>

Author: 3 people

frontend/src/lib/components/sidebar/SessionList.svelte

@@ -992,7 +992,7 @@
     font-size: 10px;
     font-weight: 600;
     color: var(--text-muted);
-    text-transform: capitalize;
+    text-transform: none;
     letter-spacing: 0.02em;
     background: var(--bg-inset);
     border-bottom: 1px solid var(--border-muted);