Phase 6+7: Inno Setup installer + GitHub Actions release pipeline

installer/webhook-server.iss is an Inno Setup 6 script that:
- Installs to %ProgramFiles%\WebhookServer
- Creates Start Menu folder + GUI shortcut (and optional desktop icon)
- Runs install-service.ps1 post-install to register the Windows Service
- Runs uninstall-service.ps1 pre-uninstall to remove it
- Bundles the webhook-server icon for the installer / uninstaller

scripts/build-installer.ps1 is the local build helper: publishes both
projects, finds ISCC.exe (PATH or standard install path), compiles the
installer with the version pulled from Directory.Build.props, drops the
output in dist/.

.github/workflows/ci.yml runs build + test on every push/PR to main.
.github/workflows/release.yml triggers on v* tags (or manual dispatch),
runs tests, installs Inno Setup via choco, builds the installer, and
attaches the .exe to a GitHub Release. Pre-1.0 versions are flagged
prerelease automatically.

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

installer/webhook-server.iss

@@ -0,0 +1,79 @@
+; Inno Setup script for Webhook Server.
+;
+; Build: iscc /DAppVersion=0.1.0 webhook-server.iss
+; Output: ..\dist\WebhookServer-Setup-{AppVersion}.exe
+;
+; The installer copies published binaries to {pf}\WebhookServer, installs the
+; Windows Service via install-service.ps1 post-install, and removes the service
+; via uninstall-service.ps1 pre-uninstall. Start Menu gets a single GUI shortcut.
+
+#ifndef AppVersion
+  #define AppVersion "0.1.0"
+#endif
+
+#define AppName "Webhook Server"
+#define AppPublisher "Justin Paul"
+#define AppURL "https://jpaul.me"
+#define AppExeName "WebhookServer.Gui.exe"
+#define ServiceExeName "WebhookServer.Service.exe"
+#define ServiceName "WebhookServer"
+#define RepoRoot "..\"
+
+[Setup]
+AppId={{6E3B3C1A-9C20-4F50-B6A8-2B6D6D7E2F11}
+AppName={#AppName}
+AppVersion={#AppVersion}
+AppPublisher={#AppPublisher}
+AppPublisherURL={#AppURL}
+AppSupportURL=https://github.com/recklessop/webhook-server
+AppUpdatesURL=https://github.com/recklessop/webhook-server/releases
+DefaultDirName={autopf}\WebhookServer
+DefaultGroupName={#AppName}
+DisableProgramGroupPage=yes
+OutputBaseFilename=WebhookServer-Setup-{#AppVersion}
+OutputDir={#RepoRoot}dist
+SetupIconFile={#RepoRoot}resources\webhook-server.ico
+UninstallDisplayIcon={app}\{#AppExeName}
+PrivilegesRequired=admin
+ArchitecturesAllowed=x64compatible
+ArchitecturesInstallIn64BitMode=x64compatible
+Compression=lzma2/max
+SolidCompression=yes
+WizardStyle=modern
+VersionInfoVersion={#AppVersion}.0
+VersionInfoCompany={#AppPublisher}
+VersionInfoProductName={#AppName}
+
+[Languages]
+Name: "english"; MessagesFile: "compiler:Default.isl"
+
+[Tasks]
+Name: "desktopicon"; Description: "Create a &desktop shortcut"; GroupDescription: "Additional shortcuts:"; Flags: unchecked
+
+[Files]
+Source: "{#RepoRoot}publish\service\*"; DestDir: "{app}"; Flags: ignoreversion recursesubdirs createallsubdirs
+Source: "{#RepoRoot}publish\gui\*";     DestDir: "{app}"; Flags: ignoreversion recursesubdirs createallsubdirs
+Source: "{#RepoRoot}scripts\install-service.ps1";   DestDir: "{app}\scripts"; Flags: ignoreversion
+Source: "{#RepoRoot}scripts\uninstall-service.ps1"; DestDir: "{app}\scripts"; Flags: ignoreversion
+Source: "{#RepoRoot}README.md"; DestDir: "{app}"; Flags: ignoreversion
+Source: "{#RepoRoot}resources\webhook-server.ico"; DestDir: "{app}"; Flags: ignoreversion
+
+[Icons]
+Name: "{group}\{#AppName}"; Filename: "{app}\{#AppExeName}"; IconFilename: "{app}\webhook-server.ico"
+Name: "{group}\Uninstall {#AppName}"; Filename: "{uninstallexe}"
+Name: "{commondesktop}\{#AppName}"; Filename: "{app}\{#AppExeName}"; IconFilename: "{app}\webhook-server.ico"; Tasks: desktopicon
+
+[Run]
+Filename: "powershell.exe"; \
+    Parameters: "-NoProfile -ExecutionPolicy Bypass -File ""{app}\scripts\install-service.ps1"" -BinaryPath ""{app}\{#ServiceExeName}"""; \
+    StatusMsg: "Installing Windows Service..."; \
+    Flags: runhidden
+Filename: "{app}\{#AppExeName}"; \
+    Description: "Launch {#AppName}"; \
+    Flags: postinstall nowait skipifsilent
+
+[UninstallRun]
+Filename: "powershell.exe"; \
+    Parameters: "-NoProfile -ExecutionPolicy Bypass -File ""{app}\scripts\uninstall-service.ps1"""; \
+    Flags: runhidden; \
+    RunOnceId: "RemoveWebhookService"