[codex] Implement Pro locked control entry

[uniplanck]

Summary

• Added a reusable Pro locked preference control for Appearance.
• Replaced the previous static Appearance upgrade panel with a gated control entry.

Files changed

• Clipy/Sources/Preferences/CPYPreferencesWindowController.swift

UI pattern added

• BoardManPreferenceProLockedControlView shows a title, lock/fallback, PRO badge, helper copy, disabled hosted control, and Upgrade CTA when locked.

Entitlement source used

• Uses central EntitlementGate.canUse(.appearanceAdvanced).

Free behavior

• Advanced Appearance remains visible.
• The hosted Appearance popup is disabled and dimmed.
• Lock indicator, PRO badge, helper text, and Upgrade CTA are visible.
• Upgrade CTA opens the existing Board-Man Pro route.

Pro structural behavior

• The same component enables its hosted control when the central entitlement allows .appearanceAdvanced.
• No fake Pro toggle or UserDefaults Pro override was added.

Validation results

• git status --short inspected; unrelated _copy/ left untouched.
• git diff --stat inspected.
• git diff --check passed.
• rtk xcodebuild -project Board-Man.xcodeproj -scheme Board-Man -configuration Debug -derivedDataPath "${TMPDIR:-/tmp}/BoardManCodexValidation" -destination 'generic/platform=macOS' -skipPackagePluginValidation -skipMacroValidation CODE_SIGNING_ALLOWED=NO build passed.

Explicitly out of scope

• Appearance full redesign
• real license activation
• backend activation
• Keychain device binding
• purchase flow
• Sparkle release/appcast