Add installer/installer.iss (Inno Setup 6 minimal)

Produces drover-vX.Y.Z-setup.exe via `iscc /DMyAppVersion=X.Y.Z installer/installer.iss`.

- Stable AppId UUID for upgrade compatibility
- Bundles drover.exe, WinDivert.dll/sys, LICENSE, README, WinDivert-LGPL
- English + Russian wizard languages
- Optional desktop icon and Windows autostart tasks
- HKCU registry entry for updater install-path discovery
- Best-effort service stop/uninstall on uninstall
- ARM64 refusal in [Code] InitializeSetup (WinDivert has no ARM64 build)
- Requires admin (kernel driver install), x64-compatible only, Win10 1809+

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

installer/installer.iss

@@ -0,0 +1,75 @@
+; Drover-Go Inno Setup 6 installer script.
+; Compile from repo root: iscc /DMyAppVersion=0.1.0 installer/installer.iss
+
+#ifndef MyAppVersion
+  #define MyAppVersion "0.0.0-dev"
+#endif
+
+[Setup]
+AppId={{B5F4D8A7-3C2E-4F18-9B6A-8E7C5D1F0A23}
+AppName=Drover-Go
+AppVersion={#MyAppVersion}
+AppVerName=Drover-Go {#MyAppVersion}
+AppPublisher=okcu.io
+AppPublisherURL=https://git.okcu.io/root/drover-go
+AppSupportURL=https://git.okcu.io/root/drover-go/issues
+AppUpdatesURL=https://git.okcu.io/root/drover-go/releases
+DefaultDirName={autopf}\Drover-Go
+DefaultGroupName=Drover-Go
+OutputDir=Output
+OutputBaseFilename=drover-{#MyAppVersion}-setup
+Compression=lzma2
+SolidCompression=yes
+WizardStyle=modern
+PrivilegesRequired=admin
+ArchitecturesAllowed=x64compatible
+ArchitecturesInstallIn64BitMode=x64compatible
+LicenseFile=..\LICENSE
+MinVersion=10.0.17763
+UninstallDisplayName=Drover-Go {#MyAppVersion}
+UninstallDisplayIcon={app}\drover.exe
+CloseApplications=yes
+RestartIfNeededByRun=no
+
+[Languages]
+Name: "english"; MessagesFile: "compiler:Default.isl"
+Name: "russian"; MessagesFile: "compiler:Languages\Russian.isl"
+
+[Tasks]
+Name: "desktopicon"; Description: "{cm:CreateDesktopIcon}"; GroupDescription: "{cm:AdditionalIcons}"; Flags: unchecked
+Name: "autostart"; Description: "Start Drover-Go automatically with Windows"; GroupDescription: "Startup:"; Flags: unchecked
+
+[Files]
+Source: "..\drover.exe"; DestDir: "{app}"; DestName: "drover.exe"; Flags: ignoreversion
+Source: "..\LICENSE"; DestDir: "{app}"; DestName: "LICENSE.txt"; Flags: ignoreversion
+Source: "..\README.md"; DestDir: "{app}"; DestName: "README.md"; Flags: ignoreversion
+Source: "..\third_party\windivert\WinDivert.dll"; DestDir: "{app}"; DestName: "WinDivert.dll"; Flags: ignoreversion
+Source: "..\third_party\windivert\WinDivert64.sys"; DestDir: "{app}"; DestName: "WinDivert64.sys"; Flags: ignoreversion
+Source: "..\third_party\windivert\LICENSE-LGPL"; DestDir: "{app}"; DestName: "WinDivert-LICENSE.txt"; Flags: ignoreversion
+
+[Icons]
+Name: "{group}\Drover-Go"; Filename: "{app}\drover.exe"
+Name: "{group}\{cm:UninstallProgram,Drover-Go}"; Filename: "{uninstallexe}"
+Name: "{commondesktop}\Drover-Go"; Filename: "{app}\drover.exe"; Tasks: desktopicon
+Name: "{userstartup}\Drover-Go"; Filename: "{app}\drover.exe"; Parameters: "service start"; Tasks: autostart
+
+[Registry]
+Root: HKCU; Subkey: "Software\Drover-Go"; ValueType: string; ValueName: "InstallPath"; ValueData: "{app}"; Flags: uninsdeletevalue
+
+[Run]
+Filename: "{app}\drover.exe"; Description: "{cm:LaunchProgram,Drover-Go}"; Flags: postinstall skipifsilent nowait
+
+[UninstallRun]
+Filename: "{app}\drover.exe"; Parameters: "service stop"; Flags: runhidden skipifdoesntexist; RunOnceId: "StopService"
+Filename: "{app}\drover.exe"; Parameters: "service uninstall"; Flags: runhidden skipifdoesntexist; RunOnceId: "UninstallService"
+
+[Code]
+function InitializeSetup(): Boolean;
+begin
+  Result := True;
+  if ProcessorArchitecture = paArm64 then
+  begin
+    MsgBox('Drover-Go requires a native x64 Windows installation. ARM64 is not supported because WinDivert (the underlying packet capture driver) does not have an ARM64 build.', mbCriticalError, MB_OK);
+    Result := False;
+  end;
+end;