feat(ui): implement adaptive system theme preferences with live AppKi…

[kerem0x]

Description

This pull request introduces comprehensive native theme configuration support (System Theme, Light, Dark) to OpenTamer. It transitions the utility's surface design from a hardcoded Aqua configuration to a fully dynamic, adaptive workspace interface that seamlessly handles dark environment canvases under professional macOS AppKit standards.

Additionally, this PR addresses micro-alignment styling imbalances inside process dashboard lists and introduces interactive theme hot-reloading.

Key Changes

🛠️ 1. Core Logic & Schema Layer (internal/core/, internal/config/)

• Added Theme parameter to core.GlobalPreferences struct with defensive input string text validation.
• Updated internal/config/config.go configuration loaders to automatically inject "system" defaults into clean application profiles.
• Wrote automatic backward-compatible schema migration handlers inside LoadConfig() to backfill legacy configuration configurations safely without erasing user settings.
• Added comprehensive lifecycle validation tests to config_test.go.

⚙️ 2. UI Coordination (internal/ui/)

• Registered PreferenceTheme identifiers within the interface controller routing.
• Updated setStringPreference map handlers to cleanly forward string changes to state engines.

🍏 3. Native macOS Presentation Bridge (internal/macos/)

• Adaptive Render Blocks: Modified menu_bar_bridge.m to pull adaptive semantic assets (like [NSColor labelColor]) dynamically. Restructured custom canvas surfaces (OpenTamerPanelView, OpenTamerCPUGraphView) and action buttons to alter frame tones depending on the OS container state context.
• CGO Linking Enhancements: Extended compiler LDFLAGS inside menu_bar_darwin.go to pull Apple's native QuartzCore library during assembly runs.
• Safeguard Verification Tests: Updated menu_bar_preferences_test.go to cleanly add the "theme" element key safely inside the dashboard's alphabetized whitelist checks.

🎨 Visual Polish & UI/UX Optimizations

📐 Pixel-Perfect Vertical Centering

• Adjusted textual row drawing bounding limits inside drawProcessAction from a +6 vertical offset down to +2, preventing text labels from crowding or clipping row lines.
• Recalibrated row status indicator circles from +8 down to +6 vertical origin coordinates to ensure indicator symbols rest symmetrically.

⚡ Instant Live Hot-Reloading

• Modified OpenTamerCommandShouldKeepMenuOpen bounds to drop selection tracking loops immediately when changing app themes.
• This frees graphic animation update blocks and allows popover content elements to repaint themes immediately upon selection without requiring secondary panel interaction or window focus loss.

Status Checklist

• Manual smoke testing performed across multiple screen loops.
• All automated configurations and schema tests passing cleanly (go test ./...).
• Code structured cleanly and formatted using standard Go ecosystem parameters.

Verification Steps

1. Spin up the application manually using developer parameters: OPENTAMER_ALLOW_DIRECT_LAUNCH=1 ./opentamer
2. Open the control panel, click into Preferences ➡️ General ➡️ Theme.
3. Select Dark / Light / System Theme. Verify that rows format symmetrically, text blocks center, and layouts redraw design languages instantly.