feat(ui): port retail gameplay indicator bar

Promote all seven LayoutDesc 0x21000071 controls to retained buttons, drive link quality, effects, Vitae, and burden from live state, and route Character Information plus end-session confirmation through the shared UI owners. Keep network timing in WorldSession and pin retail thresholds, flash cadence, authored states, and action routing with focused conformance tests.

Release build and all 5,807 tests pass with five intentional skips. Connected visual gate pending.

Co-authored-by: OpenAI Codex <codex@openai.com>

src/AcDream.Core.Net/LinkStatusSnapshot.cs

@@ -0,0 +1,13 @@
+namespace AcDream.Core.Net;
+
+/// <summary>
+/// Immutable network-owned input for retail's link-status presentation.
+/// <see cref="WorldSession"/> records the last successfully decoded server
+/// datagram; UI code applies retail's display thresholds and cadence.
+/// </summary>
+public readonly record struct LinkStatusSnapshot(
+    bool Connected,
+    double SecondsSinceLastPacket)
+{
+    public static LinkStatusSnapshot Disconnected => new(false, 0d);
+}