#6 Remove lock-screen support

Removes all lock-screen functionality. The notch is now a normal window and does not appear or do anything on the lock screen.

• Deleted showOnLockScreen (Defaults key, settings toggle, localized string); the stale value is removed from UserDefaults on launch.
• Deleted SkyLight/CGSSpace code (BoringNotchSkyLightWindow → plain BoringNotchWindow, CGSSpace, NotchSpaceManager) and the SkyLightWindow package. SkyLight was only used for the lock screen.
• Removed the lock/unlock distributed-notification observers and the close/recreate-windows-on-lock logic.
• applyOSDSources no longer checks for an empty notch space (only relevant to lock cleanup).
• Docs: removed VISION item 3 and lock-screen order-of-work entries, noted #1346/#1498 are irrelevant, added a "no lock-screen support" Not goal. Item numbers left unchanged so references stay valid.
• ContentView untouched, to avoid conflicts with #1.

Verified: scripts/dev.sh build succeeds. Lock/unlock behavior is not verifiable by build.

🤖 Generated with Claude Code

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Summary by cubic

Removes all lock-screen support so the notch is a normal window and never appears on the lock screen.

Changes

• Deletes the showOnLockScreen setting (Defaults key, settings toggle, and localized strings); the stale value is removed from UserDefaults on launch.
• Removes the SkyLight/CGSSpace machinery: BoringNotchSkyLightWindow is now plain BoringNotchWindow, and CGSSpace, NotchSpaceManager and the SkyLightWindow package are gone.
• Removes the lock/unlock distributed-notification observers and the related window close/recreate logic.
• applyOSDSources no longer checks for an empty notch space.
• Updates VISION, AGENTS and sync docs to drop lock-screen references and adds a "no lock-screen support" Not goal.