Migrate Foliary desktop app to Nucleus 2

[MessiasLima]

Description

Upgrade the desktop app from Nucleus 1.x to Nucleus 2 so Foliary uses the current plugin ID, Maven coordinates, package namespace, and application bootstrap model. The current desktop entry point still relies on application {} plus manual deep-link and single-instance handling; Nucleus 2 replaces that with nucleusApplication(args), automatic bootstrap, and renamed dev.nucleusframework APIs. This migration should preserve current desktop behavior while reducing custom startup plumbing and aligning follow-up desktop work, including AOT cache setup, with the supported API surface.

Scope and constraints

• Migrate the desktop module from Nucleus 1.15.6 / io.github.kdroidfilter.* to Nucleus 2 / dev.nucleusframework.*
• Update the Gradle plugin ID, dependency coordinates, DSL imports, and Kotlin imports touched by the migration
• Replace the current desktop startup path in desktop/src/main/kotlin/Main.kt with nucleusApplication(args) and move deep-link handling to the Nucleus 2 API
• Remove or adapt manual single-instance and restore logic in ManageSingleInstance.kt and DecoratedWindow.kt where Nucleus 2 now provides the behavior automatically
• Preserve the current Material 3 decorated window, tray integration, deep-link dispatch, and packaging targets
• Do not expand scope into unrelated desktop UX changes, auto-update work, or non-desktop platform changes
• If the selected Nucleus 2 artifacts require extra repository or toolchain changes, include only the minimal build changes needed for this migration

References

• Nucleus migration guide: https://nucleusframework.dev/en/docs/migrate/from-1.x/
• Related issue: Setup Nucleus for Desktop Builds #25
• Related issue: Enable AOT cache for desktop application startup #102
• Current version catalog: gradle/libs.versions.toml
• Current desktop bootstrap: desktop/src/main/kotlin/Main.kt

Scope

In scope: version/catalog updates, package and import renames, desktop bootstrap migration, removal of 1.x-only startup plumbing, and validation that desktop runtime behavior still works under Nucleus 2.

Out of scope: redesigning window or tray UX, enabling new optional Nucleus features, changing packaging targets, or making Android/iOS-specific changes unrelated to shared import updates.

Acceptance criteria

• Foliary uses Nucleus 2 plugin and dependency coordinates instead of the current io.github.kdroidfilter 1.x setup, and all migrated imports compile under the dev.nucleusframework namespace
• The desktop app starts through nucleusApplication(args) and uses the Nucleus 2 deep-link API instead of manual DeepLinkHandler.register(...) bootstrap in Main.kt
• Manual 1.x-only single-instance / restore plumbing is removed or reduced to only behavior still required by Foliary, while second-launch restore and deep-link delivery continue to work
• Existing desktop packaging configuration still resolves and remains compatible with the migration
• Any additional repository or JVM toolchain requirements discovered during the migration are applied only where needed and documented in the implementation
• Follow-up AOT cache work is aligned with the Nucleus 2 bootstrap model so issue Enable AOT cache for desktop application startup #102 no longer depends on 1.x-specific startup assumptions

Additional information

Current files likely touched by this migration include:

• gradle/libs.versions.toml
• desktop/build.gradle.kts
• desktop/src/main/kotlin/Main.kt
• desktop/src/main/kotlin/ManageSingleInstance.kt
• desktop/src/main/kotlin/DeeplinkHandler.kt
• desktop/src/main/kotlin/DecoratedWindow.kt
• foliary/src/jvmMain/kotlin/dev/appoutlet/foliary/feature/main/MainScreen.jvm.kt

The current codebase does not appear to use Jewel-specific window components, so JDK 25 and the IntelliJ snapshots repository should be treated as conditional migration requirements rather than assumed baseline changes.