feat(postit): add per-user Windows NSIS installer

Package the self-contained Windows x64 publication, register the postit URI scheme, and provide a Start menu shortcut and uninstaller. Document generation and update the changelog.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

contrib/Windows/postit.nsi

@@ -0,0 +1,114 @@
+Unicode true
+RequestExecutionLevel user
+SetCompressor /SOLID lzma
+
+!include "MUI2.nsh"
+!include "LogicLib.nsh"
+!include "x64.nsh"
+
+!define APPNAME "PostIt.Desktop"
+!define APP_EXE "PostIt.Desktop.exe"
+!define PUBLISHER "Yavsc"
+!define UNINSTALL_KEY "Software\Microsoft\Windows\CurrentVersion\Uninstall\${APPNAME}"
+!define PROTOCOL_KEY "Software\Classes\postit"
+
+!ifndef APP_VERSION
+  !error "Define APP_VERSION with /DAPP_VERSION=... (Windows) or -DAPP_VERSION=... (Linux)."
+!endif
+!ifndef PUBLISH_DIR
+  !define PUBLISH_DIR "..\..\src\PostIt\PostIt.Desktop\bin\Release\net10.0\win-x64\publish"
+!endif
+!ifndef OUTPUT_FILE
+  !define OUTPUT_FILE "PostIt-${APP_VERSION}-win-x64-Setup.exe"
+!endif
+!if ! /FileExists "${PUBLISH_DIR}\${APP_EXE}"
+  !error "Publish PostIt.Desktop for win-x64 before compiling the installer (see INSTALL.md)."
+!endif
+
+Name "${APPNAME}"
+OutFile "${OUTPUT_FILE}"
+InstallDir "$LOCALAPPDATA\${PUBLISHER}\${APPNAME}"
+InstallDirRegKey HKCU "${UNINSTALL_KEY}" "InstallLocation"
+ShowInstDetails show
+ShowUninstDetails show
+
+!define MUI_ABORTWARNING
+!define MUI_ICON "..\..\src\PostIt\PostIt\Assets\yavsc-logo.ico"
+!insertmacro MUI_PAGE_WELCOME
+!insertmacro MUI_PAGE_INSTFILES
+!insertmacro MUI_PAGE_FINISH
+!insertmacro MUI_UNPAGE_CONFIRM
+!insertmacro MUI_UNPAGE_INSTFILES
+!insertmacro MUI_LANGUAGE "French"
+
+Function .onInit
+  SetShellVarContext current
+  ${IfNot} ${RunningX64}
+    MessageBox MB_OK|MB_ICONSTOP "Cette version de PostIt.Desktop requiert Windows 64 bits." /SD IDOK
+    Abort
+  ${EndIf}
+FunctionEnd
+
+Function un.onInit
+  SetShellVarContext current
+FunctionEnd
+
+Section "PostIt.Desktop"
+  ; Keep the recursive payload separate from user data and the uninstaller.
+  ClearErrors
+  SetOutPath "$INSTDIR\app"
+  ${If} ${Errors}
+    MessageBox MB_OK|MB_ICONSTOP "Impossible de creer le dossier d'installation. Verifiez les droits d'ecriture, puis relancez l'installation." /SD IDOK
+    Abort
+  ${EndIf}
+  File /r "${PUBLISH_DIR}\*"
+  WriteUninstaller "$INSTDIR\uninstall.exe"
+  ${If} ${Errors}
+    MessageBox MB_OK|MB_ICONSTOP "Installation impossible. Fermez PostIt.Desktop et verifiez les droits d'ecriture et l'espace disque, puis relancez l'installation." /SD IDOK
+    Abort
+  ${EndIf}
+
+  ClearErrors
+  CreateDirectory "$SMPROGRAMS\${PUBLISHER}"
+  CreateShortcut "$SMPROGRAMS\${PUBLISHER}\${APPNAME}.lnk" "$INSTDIR\app\${APP_EXE}"
+
+  WriteRegStr HKCU "${PROTOCOL_KEY}" "" "URL:PostIt"
+  WriteRegStr HKCU "${PROTOCOL_KEY}" "URL Protocol" ""
+  WriteRegStr HKCU "${PROTOCOL_KEY}\DefaultIcon" "" '"$INSTDIR\app\${APP_EXE}",0'
+  WriteRegStr HKCU "${PROTOCOL_KEY}\shell\open\command" "" '"$INSTDIR\app\${APP_EXE}" "%1"'
+
+  WriteRegStr HKCU "${UNINSTALL_KEY}" "DisplayName" "${APPNAME}"
+  WriteRegStr HKCU "${UNINSTALL_KEY}" "DisplayVersion" "${APP_VERSION}"
+  WriteRegStr HKCU "${UNINSTALL_KEY}" "Publisher" "${PUBLISHER}"
+  WriteRegStr HKCU "${UNINSTALL_KEY}" "DisplayIcon" '"$INSTDIR\app\${APP_EXE}",0'
+  WriteRegStr HKCU "${UNINSTALL_KEY}" "UninstallString" '"$INSTDIR\uninstall.exe"'
+  WriteRegStr HKCU "${UNINSTALL_KEY}" "QuietUninstallString" '"$INSTDIR\uninstall.exe" /S'
+  WriteRegStr HKCU "${UNINSTALL_KEY}" "InstallLocation" "$INSTDIR"
+  WriteRegDWORD HKCU "${UNINSTALL_KEY}" "NoModify" 1
+  WriteRegDWORD HKCU "${UNINSTALL_KEY}" "NoRepair" 1
+  ${If} ${Errors}
+    MessageBox MB_OK|MB_ICONSTOP "Impossible de creer les raccourcis ou les entrees du registre utilisateur. Relancez l'installation." /SD IDOK
+    Abort
+  ${EndIf}
+SectionEnd
+
+Section "Uninstall"
+  SetOutPath "$TEMP"
+  ClearErrors
+  RMDir /r "$INSTDIR\app"
+  ${If} ${Errors}
+    MessageBox MB_OK|MB_ICONSTOP "Des fichiers n'ont pas pu etre supprimes. Fermez PostIt.Desktop, puis relancez la desinstallation." /SD IDOK
+    Abort
+  ${EndIf}
+
+  ; Do not remove a protocol handler subsequently registered by another install.
+  ReadRegStr $0 HKCU "${PROTOCOL_KEY}\shell\open\command" ""
+  ${If} $0 == '"$INSTDIR\app\${APP_EXE}" "%1"'
+    DeleteRegKey HKCU "${PROTOCOL_KEY}"
+  ${EndIf}
+  Delete "$SMPROGRAMS\${PUBLISHER}\${APPNAME}.lnk"
+  RMDir "$SMPROGRAMS\${PUBLISHER}"
+  DeleteRegKey HKCU "${UNINSTALL_KEY}"
+  Delete "$INSTDIR\uninstall.exe"
+  RMDir "$INSTDIR"
+SectionEnd