Bump to v3.1.1: tray tooltip 'starting up' could get stuck after first launch

Bug: if v3.1 installed via auto-update on a profile with StartMinimised
on, the tray icon's hover tooltip got stuck at the initial "RemSound -
starting up" string. The snapshot tick was running and SetTooltip was
being called every second with the live state, but Windows shell kept
showing the original cached text on hover. The fix-by-workaround was a
hide-then-re-show cycle which forced the shell to rebuild the icon
registration with the latest NotifyIcon.Text.

Root cause: NotifyIcon.Text values set BEFORE the icon's first
NIM_ADD (i.e. while Visible=false) become the shell's "initial"
tooltip when the icon eventually appears. Subsequent NIM_MODIFY calls
from text changes DO propagate, but the shell tends to keep showing
the original text on hover - presumably a tooltip-cache eviction
quirk. In the resume-after-update-with-StartMinimised flow, the
window briefly shows then BeginInvokes a Minimize that flips
Visible=true before the snapshot timer has had a chance to fire, so
the shell registers with the stale "starting up" string.

Fix: drop the hard-coded "starting up" initial text from the
controller ctor entirely. The controller now takes a Func<string>
buildTooltip callback from MainForm and calls it in Minimize() right
before flipping Visible=true, so the shell's NIM_ADD sees current
live state instead of a stale string. The 1 Hz snapshot tick keeps
working for ongoing live updates while the icon is visible.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/RemSound.App/RemSound.App.csproj

@@ -14,7 +14,7 @@
          tag_name on the latest GitHub release; bump it on every public release. The
          AssemblyVersion / FileVersion default to this value, and Assembly.GetName().Version
          is what the About dialog and the updater both read. -->
-    <Version>3.1.0</Version>
+    <Version>3.1.1</Version>
   </PropertyGroup>
 
   <ItemGroup>