docs(roadmap): add platformdirs config dir layout under D-01

D-01 now explicitly lists the four files that live in the per-user
config directory (%APPDATA%\bibliogon\ on Windows, equivalent paths
on macOS/Linux):
- install.json (manifest)
- install.log (rotating activity log)
- cleanup.json (only during interrupted uninstall)
- settings.json (user preferences, added by the D-04 follow-up)

Also notes that D-01 covers the opt-out settings from the D-04
follow-up. This is the final piece from "update ROADMAP to current
state" - everything else was already reflected in cc1d65a.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: astrapisixtynine

docs/ROADMAP.md

@@ -28,7 +28,7 @@ Bugs whose impact on shipped versions warrants tracking separately from polish w
 
 Lower the installation barrier for non-technical users. Simple Launcher first, Tauri as a later option if needed. No Electron. See [docs/explorations/desktop-packaging.md](explorations/desktop-packaging.md) for the full evaluation.
 
-- [x] D-01: Simple Launcher for Windows (`.exe` via PyInstaller). Install, uninstall, Docker start/stop, browser open, health check, update notification. CI: [launcher-windows.yml](../.github/workflows/launcher-windows.yml). Manual smoke test: [issue #2](https://github.com/astrapi69/bibliogon/issues/2).
+- [x] D-01: Simple Launcher for Windows (`.exe` via PyInstaller). Install, uninstall, Docker start/stop, browser open, health check, update notification, opt-out settings. CI: [launcher-windows.yml](../.github/workflows/launcher-windows.yml). Per-user state lives in `%APPDATA%\bibliogon\` with files `install.json` (manifest), `install.log` (rotating activity log), `cleanup.json` (only during interrupted uninstall), `settings.json` (user preferences). Manual smoke test: [issue #2](https://github.com/astrapi69/bibliogon/issues/2).
 - [x] D-02: Simple Launcher for macOS (`.app` bundle, arm64-only for initial release). Same source as Windows launcher; spec file's darwin BUNDLE block produces the `.app`. CI: [launcher-macos.yml](../.github/workflows/launcher-macos.yml). Unsigned binary requires Gatekeeper bypass (right-click -> Open) on first launch. Intel Mac support (universal2) and code signing deferred until user demand. Manual smoke test: [issue #3](https://github.com/astrapi69/bibliogon/issues/3).
 - [x] D-03: Simple Launcher for Linux (PyInstaller binary). Same source as Windows launcher; spec file is cross-platform aware. CI: [launcher-linux.yml](../.github/workflows/launcher-linux.yml). Requires `python3-tk` on target (preinstalled on every major desktop distro). Optional follow-up: `.desktop` file for GNOME/KDE menu integration. Manual smoke test: [issue #4](https://github.com/astrapi69/bibliogon/issues/4).
 - [ ] D-03a: AppImage for Linux — deferred. The PyInstaller binary requires `python3-tk` on the target (preinstalled on every major desktop distro). AppImage would make that self-contained at a 4-10x size cost and added CI complexity (FUSE + appimagetool). Re-evaluate only when a user reports a missing-tkinter failure in the wild.