Plugins: add editable native editor compatibility rules

[emaspa]

Changes

• Add a curated native-editor compatibility policy, initially blocking the Elgato De-Esser VST3 editor.
• Keep audio processing, native hosting, parameters and bypass choices unchanged. Blocked cogs open OpenXLR controls, and the daemon refuses direct native-editor requests.
• Edit the list from Options or the Native editors shortcut beside Bypass in a blocked controls window, with the current plugin selected.
• Store only explicit user overrides. Untouched plugins follow future release defaults; user allow/block choices survive until reset to the release default.
• Save atomically, preserve policy on failed writes, reject damaged configuration without overwriting it, and update editor availability live without rescanning plugins.
• Isolate environment-mutating tests from parallel helper processes.

Verification

• Native-enabled Release build passed with 0 warnings and 0 errors.
• Policy, persistence, API, notification and editor-only availability tests passed. The combined local suite passed 510 tests; the two button-label tests belong to the separate cleanup commit.
• Xvfb layout checks passed for narrow/wide windows and the shortcut's placement and plugin preselection.
• Live API returned the curated De-Esser block and refused its native editor; mixer and window settings were preserved.
• Local deployment verified. No Wine patch or runtime override was installed.

No version bump or release changes. Button-label cleanup is separate.