Empty catch blocks silently swallow errors in dashboard

[CalebisGross]

Problem

`internal/web/static/index.html` has multiple patterns like:

• `catch (e) {}` — completely silent
• `catch (e) { console.error(...) }` — logs to console but no user feedback

Found at multiple locations including insights loading, WebSocket message handling, and project loading.

Impact

When graph data, agent data, or other resources fail to load, the user sees no error message. Features silently fail.

Fix

Add user-visible error notifications (toast/banner) for all catch blocks that affect UI state.