feat: prepare WinIsland 1.3.9 interaction and display updates

[FoOcean]

Pre-submission checklist

• I have read CONTRIBUTING.md and completed the required checks
• Local and CI checks pass (local checks pass; CI is pending)
• I have completed a self-review
• I confirm that I haven't read the checkboxes and just ticked them all

Change type (select one)

• feat New feature
• fix Bug fix
• docs Documentation or templates
• style Formatting with no behavior change
• refactor Code change that neither fixes a bug nor adds a feature
• perf Performance improvement
• test Test-related change
• chore Build, CI, dependency, or tooling change
• revert Revert
• security Security fix

Scope (select all that apply)

• Application core
• UI style or layout
• Application behavior
• Dependency changes (additional Windows API features)
• Plugin API
• CI/CD configuration
• Documentation
• Other (describe below)

Related issues

None linked.

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Description

Summary

Prepare WinIsland 1.3.9 with separate inactivity and fullscreen hiding, compact-island content gestures, system brightness overlays, and fixes for display, media, and settings interactions.

Motivation and context

The previous auto-hide option combined unrelated behavior; compact content could not be dismissed independently, and mixed-DPI monitors could move or resize Settings unexpectedly. Media progress and lyrics also had edge cases. This PR collects the tested 1.3.9 changes on a branch created from the current master.

Changes

• Split auto-hide into inactivity and fullscreen options. Fullscreen hiding blocks manual reveal but still temporarily shows volume and brightness adjustments. The brief yellow outline now appears only while entering fullscreen hide.
• Add horizontal swiping on the compact island to hide or restore media and widgets. Swipe detection stays separate from vertical hiding; tapping still opens the expanded island, where content remains visible. Hidden compact content uses the default black background.
• Add an internal-display brightness indicator and dragging, refine volume spacing, and fix media progress at the zero and full positions.
• Keep the island and Settings correctly positioned on mixed-DPI monitors; improve touch input and make Settings scrolling follow input without application inertia.
• Convert fetched lyrics to simplified Chinese only for the Chinese UI, add the NetEase SMTC notice, and refine widget rendering and resource animations.
• Bump the application and lockfile versions to 1.3.9. Older configurations migrate the previous auto_hide value into the new fullscreen option; the brightness overlay defaults on only when supported by the internal-display monitor.

UI changes

In compact mode, a horizontal swipe removes or restores all content without moving the island vertically. A tap still expands it. Entering fullscreen hide briefly draws a fading yellow outer outline; other activity does not. Settings scrolling stops immediately with the input. No changelog files are changed; maintainers can add the final 1.3.9 entries before running the stable release workflow.

Validation: cargo fmt --all, cargo clippy --workspace --release --offline -- -D warnings, and cargo build --release --offline passed on Windows. Mixed-DPI, touch, and internal-display brightness interactions still need physical-device review.