refactor: replace NSIS with Inno Setup for Windows installer

Switch from NSIS (early 2000s) to Inno Setup 6 — the modern standard
used by VS Code and most Electron apps. Features:

- Modern wizard UI (WizardStyle=modern)
- LZMA2/ultra64 solid compression (138.9 MB, down from 143 MB with NSIS)
- Per-user install to %LOCALAPPDATA%\Programs\Aryx (no admin needed)
- Optional desktop shortcut, Start Menu group
- Auto-closes running instance before install/uninstall
- Proper Add/Remove Programs integration via AppId
- Launch-after-install option

CI updated to install Inno Setup via Chocolatey on windows-latest.

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

.github/workflows/release.yml

@@ -131,10 +131,10 @@ jobs:
           sudo apt-get update
           sudo apt-get install -y libsecret-1-dev
 
-      - name: Install NSIS
+      - name: Install Inno Setup
         if: runner.os == 'Windows'
         shell: pwsh
-        run: choco install nsis -y --no-progress
+        run: choco install innosetup -y --no-progress
 
       - name: Install dependencies
         run: bun install --frozen-lockfile