docs: rebrand as Kotlin framework for desktop apps

Update messaging across documentation to position Nucleus as \"the Kotlin framework for native desktop apps\" rather than \"the native desktop platform for the JVM\". This better emphasizes Kotlin as the primary language and aligns with the modern developer experience.

- Update site description and main taglines
- Reorganize navigation to prioritize roadmap over changelog
- Maintain technical accuracy while improving developer appeal

Author: kdroidFilter

docs/roadmap.md

@@ -0,0 +1,13 @@
+# Roadmap
+
+Modules planned for upcoming releases. Contributions welcome.
+
+| Module | Description | macOS | Windows | Linux |
+|--------|-------------|-------|---------|-------|
+| `secure-storage` | Hardware-backed secret storage for tokens, passwords, keys | Keychain | Credential Manager / DPAPI | Secret Service (`libsecret`) |
+| `biometric-auth` | Prompt for fingerprint / face authentication | `LocalAuthentication` (Touch ID / Face ID) | Windows Hello | `fprintd` via D-Bus / polkit |
+| `share-sheet` | OS share sheet (URL, file, text) | `NSSharingService` | Windows `DataTransferManager` | xdg-desktop-portal `Share` |
+| `power-events` | Sleep / wake / lock / unlock / screen-off / battery state events | `NSWorkspace` notifications | `WM_POWERBROADCAST` / `WTSRegisterSessionNotification` | `org.freedesktop.login1` D-Bus signals |
+| `fs-watcher` | Native filesystem watcher (replaces slow `WatchService`) | `FSEvents` | `ReadDirectoryChangesW` | `inotify` |
+| `clipboard` | Rich clipboard — image, files, HTML, RTF — plus change watcher | `NSPasteboard` | `OleGetClipboard` / Clipboard History API | `wl-clipboard` / X11 selections |
+| `screen-capture` | Native screenshot / screen recording | `CGDisplayCreateImage` / ScreenCaptureKit | Windows Graphics Capture / DXGI | xdg-desktop-portal `Screenshot` |