Add notification bell to mobile sidebar

[KCarretto]

The notification bell was missing from the mobile sidebar. This PR adds the NotificationBell component to MobileNav.tsx, placing it in the sidebar footer alongside the user profile link, matching the layout used in the desktop FullSidebarNav component.

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PR created automatically by Jules for task 3003822603770566693 started by @KCarretto

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[github-actions]

Summary

Tests 📝	Passed ✅	Failed ❌	Skipped ⏭️	Other ❓	Flaky 🍂	Duration ⏱️
2946	2946	0	0	0	0	1ms

Previous Results

Build 🏗️	Result 🧪	Tests 📝	Passed ✅	Failed ❌	Skipped ⏭️	Other ❓	Flaky 🍂	Duration ⏱️
#2064	✅	2946	2946	0	0	0	0	1m 6s

Insights

Average Tests per Run	Total Flaky Tests	Total Failed	Slowest Test (p95)
2946	0	0	7m 16s

Test Changes

0 test added, 0 removed

Slowest Tests

Test 📝	Results 📊	Duration (avg) ⏱️	Duration (p95) ⏱️
eldritch-libfile: std::list_recent_impl::tests::test_list_recent_default_args	3	4m 36s	7m 16s
eldritch-libfile: std::list_recent_impl::tests::test_list_recent_default_args	3	4m 36s	7m 16s
eldritch-libfile: std::list_recent_impl::tests::test_list_recent_default_args	3	4m 36s	7m 16s
TestDockerExecutor_Build_ContextCancellation	1	6.2s	6.2s
eldritch-libsys: std::dll_inject_impl::tests::test_dll_inject_simple	1	5.2s	5.2s
TestInteractiveShell	1	5.0s	5.0s
TestOtherStreamOutput	1	5.0s	5.0s
TestDockerExecutor_Build_SimpleEcho	1	3.8s	3.8s
imix::bin/imix: tests::task_tests::test_task_streaming_error	3	3.0s	3.1s
imix::bin/imix: tests::task_tests::test_task_streaming_error	3	3.0s	3.1s

_{🎉 No failed tests in this run. | 🍂 No flaky tests in this run.}

Github Test Reporter by CTRF 💚