refactor: move webkit integration into browser engine core

[yonaries]

Summary

• move WebKit page, profile, script bridge, and download handling into Core/BrowserEngine
• update tabs and browser UI to consume BrowserPage / BrowserPageView instead of owning raw WKWebView integration
• remove legacy Features/Tabs/Web wiring and keep the tabs-specific adapter in Features/Tabs/Browser

Testing

• xcodebuild -project Ora.xcodeproj -scheme ora -configuration Debug -destination "platform=macOS" -derivedDataPath /tmp/ora-derived CODE_SIGNING_ALLOWED=NO build
• manual smoke test: browsing, navigation, tabs, downloads, privacy, passwords, and media flows

[greptile-apps]

Greptile Summary

This PR introduces a clean BrowserEngine abstraction layer in Core/BrowserEngine that encapsulates all WebKit integration (WKWebView, WKWebsiteDataStore, WKDownload, user scripts, and navigation delegation) behind framework-agnostic types. Feature modules (Tabs, Downloads, Privacy, FindInPage, Passwords, Player, Browser) are updated to consume the new BrowserPage/BrowserPageView API instead of accessing WKWebView directly, and three legacy files under Features/Tabs/Web are removed.

• The new BrowserPage class wraps WKWebView with a delegate-based API (BrowserPageDelegate) that features like tab management, downloads, and passwords can implement without importing WebKit
• Tab no longer creates a web view in its init; instead, restoreTransientState lazily initializes a BrowserPage when the tab becomes active — this is a nice improvement for startup performance
• Download handling is refactored from direct WKDownloadDelegate conformance in the navigation delegate to a callback-based BrowserDownloadTask integrated via DownloadManager.handleDownload()
• There is a potential race condition in Tab.stopMedia() where browserPage is nilled synchronously while async teardown is still in progress
• BrowserWebsiteDataType.cache maps to allWebsiteDataTypes() (including cookies), which preserves prior behavior but is a semantic mismatch in the new abstraction layer

Confidence Score: 4/5

• This PR is a well-structured refactor with one potential race condition in stopMedia; overall safe to merge with that fix.
• The refactor is thorough and consistent — all 27 files are updated coherently, the build passes, and the abstraction layer is cleanly designed. The one logic concern (stopMedia race) is unlikely to trigger in normal usage but could cause issues during rapid tab close/reopen cycles. The style suggestions are non-blocking improvements.
• ora/Features/Tabs/Models/Tab.swift — potential race condition in stopMedia() between synchronous nil assignment and async teardown completion

Important Files Changed

Filename	Overview
ora/Core/BrowserEngine/BrowserPage.swift	New core abstraction wrapping WKWebView with navigation/download/script delegation. Clean separation of WebKit concerns.
ora/Core/BrowserEngine/BrowserPageView.swift	NSViewRepresentable wrapper for BrowserPage. Faithfully ports mouse event handling from old WebView. Missing downloadManager parameter compared to old Coordinator.
ora/Core/BrowserEngine/BrowserEngine.swift	Singleton factory for profiles and pages. makeProfile creates new BrowserEngineProfile each call instead of caching, but WKWebsiteDataStore handles deduplication internally.
ora/Core/BrowserEngine/BrowserEngineProfile.swift	WebKit data store wrapper with data clearing. The .cache type maps to allWebsiteDataTypes() which is broader than just cache but matches prior behavior.
ora/Core/BrowserEngine/Scripts/OraBrowserScripts.swift	Consolidates user scripts previously in TabScriptHandler. Bridge, navigation/media, and password manager scripts cleanly organized.
ora/Features/Tabs/Models/Tab.swift	Major refactor: replaces WKWebView with BrowserPage. Init no longer creates the web view; defers to restoreTransientState. Race condition in stopMedia where browserPage is nilled before async teardown completes.
ora/Features/Tabs/Browser/TabBrowserPageDelegate.swift	New delegate bridging BrowserPage events to Tab state updates. Cleanly handles navigation phases, script messages, JS dialogs, and downloads.
ora/Features/Downloads/Services/DownloadManager.swift	New handleDownload method with callback-based BrowserDownloadTask integration. Progress timer and cleanup logic are well-structured.
ora/Features/Browser/Views/BrowserView.swift	Sidebar shield JS changed from safe callAsyncJavaScript with parameterized arguments to direct string interpolation. Values are controlled internally so no injection risk in practice.
ora/Features/Privacy/Services/PrivacyService.swift	Simplified to use BrowserEngineProfile for data clearing. Behavior preserved.

Class Diagram

%%{init: {'theme': 'neutral'}}%%
classDiagram
    class BrowserEngine {
        +shared: BrowserEngine
        +makeProfile(identifier, isPrivate) BrowserEngineProfile
        +makePage(profile, configuration, delegate) BrowserPage
    }

    class BrowserEngineProfile {
        +identifier: UUID
        +isPrivate: Bool
        +dataStore: WKWebsiteDataStore
        +clearData(ofTypes, forHost, completion)
    }

    class BrowserPage {
        -webView: WKWebView
        +delegate: BrowserPageDelegate
        +contentView: NSView
        +currentURL: URL?
        +load(URLRequest)
        +reload()
        +goBack()
        +goForward()
        +evaluateJavaScript(String)
        +takeSnapshot(configuration)
        +teardown()
    }

    class BrowserPageDelegate {
        <<protocol>>
        +decidePolicyFor(navigationAction)
        +didUpdateNavigation(event)
        +didFailNavigationWith(error)
        +didReceiveScriptMessage(message)
        +didStartDownload(download)
        +requestPermission(permission)
    }

    class TabBrowserPageDelegate {
        +tab: Tab
        +mediaController: MediaController
        +passwordCoordinator: PasswordAutofillCoordinator
    }

    class Tab {
        +browserPage: BrowserPage?
        +pageDelegate: TabBrowserPageDelegate?
        +restoreTransientState()
        +setupBrowserPageDelegate(page)
    }

    class BrowserPageView {
        +page: BrowserPage
    }

    BrowserEngine --> BrowserEngineProfile : creates
    BrowserEngine --> BrowserPage : creates
    BrowserPage --> BrowserPageDelegate : delegates to
    TabBrowserPageDelegate ..|> BrowserPageDelegate : implements
    Tab --> BrowserPage : owns
    Tab --> TabBrowserPageDelegate : owns
    BrowserPageView --> BrowserPage : wraps

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_{Last reviewed commit: e68ca61}