feat(preferences): apply auto-completion (village name suggestions) [#198]

Honour the per-user auto-completion checkboxes on the rally point and the
marketplace, where the target village is typed by name (dname field):
  - v1: own villages
  - v2: villages in the surroundings of the active village
  - v3: villages of the player's alliance members

A new Database::getAutoCompleteVillages() builds the bounded, de-duplicated
name list from the enabled categories (system accounts excluded). A shared
Templates/villageAutocomplete.tpl renders a native <datalist> consumed by
the dname input via list="dnameSuggest"; nothing is emitted when every box
is unchecked, keeping the previous behaviour. Removes the "not coded yet"
tag from the auto-completion section in the preferences form.

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

Templates/Build/17.tpl

@@ -134,7 +134,7 @@ if (isset($_GET['z'])) {
 
         <table id="target_select" class="res_target" cellpadding="1" cellspacing="1">
             <tr><td class="mer"><?php echo MERCHANT;?> <?php echo $merchantAvail;?>/<?php echo $totalMerchants;?></td></tr>
-            <tr><td class="vil"><span><?php echo VILLAGES;?>:</span> <input class="text" type="text" name="dname" value="" maxlength="30" tabindex="5"></td></tr>
+            <tr><td class="vil"><span><?php echo VILLAGES;?>:</span> <input class="text" type="text" name="dname" value="" maxlength="30" tabindex="5" list="dnameSuggest" autocomplete="off"><?php include("Templates/villageAutocomplete.tpl"); ?></td></tr>
             <tr><td class="or"><?php echo OR_;?></td></tr>
             <tr>
                 <td class="coo">