Status-bar save/action messages disappear silently

[stultus]

Area: src/lib/components/TitleBar.svelte (status message ~line 182)
Severity: High

Problem

Messages like "Document saved" are written into the status bar and auto-clear after
3 s. They pop in and out with no fade, so a user glancing away misses the only
confirmation that a save succeeded.

Suggested fix

• Fade the message in and out instead of hard-snap.
• Extend visible duration slightly (4–5 s).
• Consider a subtle dot/indicator on the save button that confirms "saved" until the
  document is dirty again.