feature(app-overhaul) stabilize routing and add device-wide Headphone EQ + UX refresh

[Vudgekek]

Summary

A broad overhaul of FineTune’s audio pipeline and popup UX.
It improves routing/process stability, removes several long-standing pain points, and adds a more powerful device-focused EQ workflow for everyday use.

Fixes

• Fixed attenuated output on multichannel devices ([Bug] Low output on Topping E2x2 OTG (8ch) while FineTune is active; normal when FineTune is off #105), so channel mapping no longer reduces perceived loudness.
• Fixed output priority behavior ([BUG] Output priority not working #130), so auto-switching now follows the intended priority order.
• Fixed helper-process apps not being processed, so Chromium/Discord-style app trees are handled correctly.
• Fixed the audible processing click on first attach, reducing startup artifacts when audio begins.
• Fixed device edit mode behavior when switching Output/Input tabs, so edit state persists as expected.
• Increased stale app retention timeout, so inactive entries are not cleared too quickly.
• Removed dead/unused code paths to reduce maintenance risk and improve runtime clarity.

Features

• Added Parametric Headphone EQ with AutoEQ profile import support.
• Added a device sample-rate menu and Bluetooth device control actions.
• Added an app exclusion menu to quickly skip selected apps from processing.
• Switched EQ scope from app-dependent to device-wide behavior.
• Added dynamic volume/speaker icons based on live volume level (including the menu bar icon).
• Included broader UI refinements and icon updates from #17.

Testing Passed

• Tested with 2+ output devices.
• Tested device hot-plug, including disconnect during active playback.
• Tested with 5+ apps playing audio simultaneously.