feat(ui): add bug report button in Help and Gitea issue template

Adds a "Report a bug" / "Segnala un bug" button (6 languages) in
Help → Info that opens the repository issue tracker in the system
browser via TopLevel.Launcher (cross-platform: desktop + Android).

Adds .gitea/ISSUE_TEMPLATE/bug_report.md — Gitea-compatible markdown
template with pre-filled sections for version, platform, network,
repro steps, expected behavior, and logs.

.gitea/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,41 @@
+---
+name: Bug Report
+about: Report a problem with Palladium Wallet
+title: "[BUG] "
+labels: bug
+---
+
+## Wallet version
+<!-- Shown in Help → Info, e.g. 1.0.0 -->
+
+
+## Platform
+<!-- Windows / Linux / Android -->
+
+
+## Network
+<!-- Mainnet / Testnet / Regtest -->
+
+
+## What happened?
+<!-- Describe the bug clearly. What did you see? What did you expect? -->
+
+
+## Steps to reproduce
+1. 
+2. 
+3. 
+
+## Expected behavior
+<!-- What should have happened instead? -->
+
+
+## Logs / error messages
+<!-- Paste any error dialogs, crash messages, or stack traces. Leave blank if none. -->
+
+```
+```
+
+## Checklist
+- [ ] I searched existing issues and this is not a duplicate
+- [ ] I reproduced this on the latest available version

src/App/Localization/Loc.cs

@@ -62,6 +62,7 @@ public sealed class Loc
             "SPV-Wallet für die Kryptowährung Palladium (PLM)."],
         ["help.tab.info"]         = ["Info",                                                               "Info",                         "Info",                                 "Info",                                     "Info",                                     "Info"],
         ["help.tab.donate"]       = ["Dona",                                                               "Donate",                       "Donar",                                "Faire un don",                             "Doar",                                     "Spenden"],
+        ["help.bug.report"]       = ["Segnala un bug",                                                     "Report a bug",                 "Informar un error",                    "Signaler un bug",                          "Reportar um bug",                          "Fehler melden"],
         ["donate.desc"]           = [
             "Se questo wallet ti è utile, considera una piccola donazione allo sviluppatore.",
             "If you find this wallet useful, consider a small donation to the developer.",

src/App/Views/MainView.axaml

@@ -1555,6 +1555,9 @@
                                                    Foreground="{DynamicResource TextSecondaryBrush}"/>
                                     </StackPanel>
                                     <TextBlock Text="{Binding Loc[help.info]}" TextWrapping="Wrap"/>
+                                    <Button Content="{Binding Loc[help.bug.report]}"
+                                            Click="OnOpenBugReportClick"
+                                            HorizontalAlignment="Left"/>
                                     <Border BorderBrush="{DynamicResource BorderSubtleBrush}"
                                             BorderThickness="0,1,0,0" Margin="0,4,0,0"/>
                                     <StackPanel Spacing="4">

src/App/Views/MainView.axaml.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Linq;
 using Avalonia;
 using Avalonia.Controls;
@@ -128,6 +129,14 @@ public partial class MainView : UserControl
             vm.IsHelpOpen = false;
     }
 
+    private async void OnOpenBugReportClick(object? sender, RoutedEventArgs e)
+    {
+        var launcher = TopLevel.GetTopLevel(this)?.Launcher;
+        if (launcher is not null)
+            await launcher.LaunchUriAsync(new Uri(
+                "https://santantonio.sytes.net/davide/PalladiumWallet/issues/new"));
+    }
+
     // Esc (desktop) or Back (Android) closes the topmost open overlay.
     protected override void OnKeyDown(KeyEventArgs e)
     {