Prompt users before granting WebExtension permissions

[culpen90]

Why

QuartzWebExtensionSupport currently grants requested install-time permissions and requested match patterns automatically. The delegate methods for later permission prompts also grant everything. That makes extension testing convenient, but it is not a good long-term privacy/security posture for a browser.

Where to start

• Sources/Quartz/QuartzWebExtensionSupport.swift
• grantInstallTimePermissions(to:)
• webExtensionController(_:promptForPermissions:in:for:completionHandler:)
• webExtensionController(_:promptForPermissionMatchPatterns:in:for:completionHandler:)

Suggested approach

Add native permission prompts that explain what an extension is asking for before granting access. A first pass can use NSAlert with Allow/Cancel and plain-language permission summaries. Longer term, Quartz can persist choices, but this issue can start with install-time and runtime prompts that avoid unconditional grants.

Acceptance criteria

• Quartz no longer silently grants all requested WebExtension permissions.
• Users see a native prompt for requested permissions and match patterns.
• Denying a prompt denies the requested permissions through WebKit's completion handler.
• The prompt copy is understandable to non-developers.
• Existing extension install and action flows still work when permissions are allowed.
• swift build succeeds.

Testing

• Install an extension that requests broad host permissions.
• Confirm Quartz shows a permission prompt.
• Confirm Allow lets the extension continue.
• Confirm Cancel/deny does not grant the requested permissions.