v2.5.1: adaptive retry for 429/502/503, socket reuse, BGP retry

- Exponential backoff retry (2s/4s/8s) for rate limits and transient errors
- BGP routes retry before failing over to next route
- Socket SO_REUSEADDR prevents 'Address already in use' crashes
- Connection reset/broken pipe also retried
- BGP route count shown at proxy startup

src/codex-launcher-gui

@@ -25,6 +25,12 @@ model_catalog_json = ""
 """
 
 CHANGELOG = [
+    ("2.5.1", "2026-05-20", [
+        "Adaptive retry for 429/502/503 errors with exponential backoff",
+        "BGP routes also retry transient errors before failing over",
+        "Proxy socket reuse — no more 'Address already in use' crashes",
+        "BGP route count shown at proxy startup",
+    ]),
     ("2.5.0", "2026-05-20", [
         "AI BGP — multi-provider routing with automatic failover",
         "Create BGP pools with ordered routes from any configured endpoint",
@@ -629,7 +635,7 @@ class LauncherWin(Gtk.Window):
         # header row
         hdr = Gtk.Box(spacing=8)
         vbox.pack_start(hdr, False, False, 0)
-        lbl = Gtk.Label(label="<b>Codex Launcher v2.5.0</b>")
+        lbl = Gtk.Label(label="<b>Codex Launcher v2.5.1</b>")
         lbl.set_use_markup(True)
         hdr.pack_start(lbl, False, False, 0)
         changelog_btn = Gtk.Button(label="Changelog")