Release v3.8: New profile (blank template renamed), password-mismatch warning stays up, IP-pinning docs

New profile: a File-menu item + Ctrl+N that loads a fresh blank template as a
new unsaved session via a LoadBlankTemplateNext handoff to Program.cs's relaunch
loop — reachable even when "start with a specific profile" boots past the picker
(issue #6). Offers to save the current profile first if dirty; deliberately
silent (no profile-switch cue).

Renamed the user-facing "blank template" to "New profile": the picker's synthetic
entry (now a distinct marker TYPE, collision-safe against a real profile named
"New profile"), the window title ("RemSound — New profile"), and the manual.

Fixed the password-mismatch warning flashing away: it's raised from the 1 Hz
statusTimer, which kept firing into the modal loop and rebuilt the peer lists
(SyncAllPeerLists) under the dialog, knocking it out of the foreground. Now the
tick is frozen while it's up, it's routed through ForegroundDialog, and a
re-entry guard ensures one warning that stays put. Audited: it was the only
popup raised from a recurring timer.

Docs: manual section "Connecting to one specific IP address (and only that one)"
explaining by-name vs by-fixed-IP and that a profile saves the exact address
(issue #7 — functionality already existed); About box + RELEASE_NOTES for v3.8;
MANUAL.md regenerated.

Co-Authored-By: Claude Opus 4.8 <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>3.7.0</Version>
+    <Version>3.8.0</Version>
   </PropertyGroup>
 
   <ItemGroup>