Testing-feedback fixes: tab order, label wording, parametric editing, recording default

* Connectivity tab order: Add peer by IP now sits right after Rename peer (before the Discovered
   list), grouped with the connected-peer actions, per Ed's requested order. Dropped the second
   section header (only the lock toggle was under it).
 * Audio I/O labels: "Set volume for all received audio" → "Master volume for received audio" (the
   code never got this rename, only the manual had). Device lists now say "audio": "...for received
   audio" and "WASAPI/ASIO audio inputs/outputs to send". Labels + AccessibleNames updated together.
 * Add EQ band dialog: the spin/edit boxes now select-all on focus, so a typed value REPLACES what's
   there instead of being inserted next to it and reverting (typing 2.5 over 4.0 now works).
 * Parametric bands list: Left/Right arrow nudge the selected band's gain by half a dB, live —
   up/down still move between bands. NVDA re-reads the band's new dB.
 * Recording settings: source list reordered to Both (top, now the default) / Received / Sent;
   display order decoupled from the RecordingSource enum. Default RecordingSettings.Source = Both.
 * Preferences: Colour theme is now first in the General tab order.

Manual updated. Build clean; --selftest passes; deployed to both test folders. Held for next release.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/RemSound.App/RemSound.App.csproj

@@ -10,6 +10,10 @@
     <ApplicationManifest>app.manifest</ApplicationManifest>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
     <ApplicationHighDpiMode>SystemAware</ApplicationHighDpiMode>
+    <!-- Modern Windows UI font app-wide (was the legacy default). Purely visual; screen-reader
+         behaviour is unaffected. Applied by ApplicationConfiguration.Initialize() to every form. -->
+    <ApplicationDefaultFont>Segoe UI, 9pt</ApplicationDefaultFont>
+    <ApplicationIcon>remsound.ico</ApplicationIcon>
     <!-- Release version. The self-updater (RemSoundUpdater) compares this against the
          tag_name on the latest GitHub release; bump it on every public release. The
          AssemblyVersion / FileVersion default to this value, and Assembly.GetName().Version
@@ -18,6 +22,9 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <!-- App icon (also set via ApplicationIcon for the exe). Embedded so the forms and the tray icon
+         can load the full multi-size icon at runtime for crisp title-bar / taskbar / tray rendering. -->
+    <EmbeddedResource Include="remsound.ico" />
     <ProjectReference Include="..\RemSound.Core\RemSound.Core.csproj" />
     <ProjectReference Include="..\RemSound.Sender\RemSound.Sender.csproj" />
     <ProjectReference Include="..\RemSound.Receiver\RemSound.Receiver.csproj" />