feat(android): blue instead of cyan, everywhere at once

Cyan came from the desktop app. On the phone the reference is the system: its global search and its own apps are blue, and an app should look like the place it runs.

Accent #3B82F6 on the same slate, with white on the accent since blue is darker than cyan. The launcher icon and the launch screen follow - a cyan padlock in front of a blue interface would have read as a different app.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

android-client/PMA.Theme.pas

@@ -23,15 +23,19 @@ uses
   System.UITypes, System.Classes, FMX.Types, FMX.Objects, FMX.StdCtrls;
 
 const
-  // Ardoise et cyan, la palette du poste Windows.
+  // Ardoise et bleu. Le poste Windows accentue en cyan ; ici c'est le bleu
+  // d'Android - celui de la recherche globale et des applications systeme.
+  // Une application mobile a deux references legitimes, celle dont elle
+  // prolonge le service et celle du systeme qui l'heberge ; pour ce qui se
+  // touche, la seconde l'emporte.
   COL_BG      = TAlphaColor($FF0F172A);   // fond general
   COL_SURFACE = TAlphaColor($FF1E293B);   // blocs poses dessus
   COL_RAISED  = TAlphaColor($FF334155);   // bouton au repos
   COL_LINE    = TAlphaColor($FF334155);   // filet des cadres
   COL_TEXT    = TAlphaColor($FFE2E8F0);
   COL_MUTED   = TAlphaColor($FF94A3B8);
-  COL_ACCENT  = TAlphaColor($FF22D3EE);
-  COL_ON_ACC  = TAlphaColor($FF042F3B);   // texte sur fond accentue
+  COL_ACCENT  = TAlphaColor($FF3B82F6);
+  COL_ON_ACC  = TAlphaColor($FFFFFFFF);   // texte sur fond accentue
 
 /// A appeler une fois, avant la creation de la forme.
 procedure ApplyDarkTheme;