fix: keep sticky layout indicator visible when pinned

[IgorArkhipov]

Problem

When pinned, the sticky Layout Indicator can disappear behind another application's window after Entropy loses focus. It also remains resizable, so its saved size can change while the user expects it to stay fixed.

Fix

• Keep the pinned viewport at the always-on-top level and disable resizing both when it opens and when pinning changes at runtime.
• On macOS, keep the indicator visible when Entropy deactivates and bring it forward when pinning is enabled.
• Hide the custom resize grip while pinned and restore normal resizing after unpinning.
• Cover the initial and transition window states with pinned and unpinned contract tests.

Verification

• cargo test layout_indicator_window — 2 passed.
• Scoped rustfmt --check src/ui/layout_indicator_window.rs and git diff --check passed.
• The full suite on the current origin/main base remains blocked by existing HID/task timing failures: 486 passed / 18 failed in parallel, and 501 passed / 3 failed single-threaded.

[kissetfall]

The window-level and resizability changes are structurally sound, and a synthetic merge onto current main passed 570/570 tests, i18n, and Clippy. One macOS state transition still needs to be made symmetrical.

Pinning calls setHidesOnDeactivate: false, but unpinning sends only WindowLevel(Normal) and Resizable(true). The native hidesOnDeactivate property therefore remains changed for the lifetime of the viewport: after a pin → unpin cycle, the unpinned indicator does not return to its previous deactivation behavior.

Please restore the native property appropriate to the unpinned state (preferably through one helper that applies both sides of the pin transition, rather than a pin-only native call) and cover the transition contract where possible.

After rebasing onto current main, please run native smoke tests on Windows, macOS, and Linux for: initial pinned launch, focus loss, pin → unpin, resize restoration, close/reopen, and persisted state. On macOS, explicitly verify both deactivation behavior and window ordering after unpin.