Expose native HttpOnly cookie queries and fix packaged Windows startup

[TIMER-err]

Summary

• add WebViewComponent.getCookies(String) returning a CompletableFuture<String> on the Swing EDT
• query the platform-native cookie store so HttpOnly cookies are included
• return only cookies applicable to the requested URL in HTTP Cookie header syntax
• support WKHTTPCookieStore on macOS, WebKitCookieManager on Linux, and ICoreWebView2CookieManager on Windows
• support Linux offscreen WebViews and return explicit unsupported errors for offscreen backends on macOS/Windows
• store Windows WebView2 data under a writable per-user %LOCALAPPDATA%\SwingWebView directory so packaged applications installed in Program Files start without elevation
• preserve WEBVIEW2_USER_DATA_FOLDER overrides and fall back to the Windows temporary directory when Local AppData is unavailable
• document credential-handling expectations, platform behavior, and the Windows user-data location

Validation

• mvn -DskipTests=false -Dmaven.test.skip=false test
• Linux native build
• runtime Linux smoke test: an HTTP server supplied an HttpOnly cookie and getCookies() retrieved it successfully
• Windows runtime smoke test using the Action-built JAR: WebView2 initialized under %LOCALAPPDATA%\SwingWebView, created EBWebView, and JavaScript evaluation returned "qplayer-webview2-ok"
• all six CI native targets and the combined JAR built successfully: macOS x64/arm64, Linux x64/arm64, Windows x64/arm64

Cross-platform build: https://github.com/TIMER-err/swingwebview/actions/runs/32698087328

[TIMER-err]

@shannah Could you review this PR?

[TIMER-err]

ok, just ignore it.

[shannah]

ignore it because it's not an issue? or ignore it because you got impatient with me responding?

[TIMER-err]

you are right, it's not a issue. i apologize if i made you feel uncomfortable. but i didnt got impatient, if you dont want to merge it, just close it.

[shannah]

Thanks @TIMER-err, this is a great addition! Your commits have been merged into master as part of #61, with your authorship preserved, so I'm closing this PR.

Because this PR comes from a fork, the follow-up fixes went into #61 as a separate branch, on top of your commits:

• macOS: the NSURL is now retained across the async getAllCookies: completion. The file is non-ARC C++, so the block wasn't retaining it, which caused a use-after-free.
• macOS: host-only cookies (domain without a leading dot) now match only that exact host, so they're no longer returned for subdomains.
• All platforms: results are ordered longest path first (RFC 6265 §5.4). WebView2's GetCookies doesn't sort by path, so Windows sorts explicitly.
• Windows: if posting the query to the WebView2 thread fails, the future now completes with an error instead of hanging.
• Windows: an existing, writable <exe>.WebView2 folder beside the executable keeps being used, so upgrading doesn't discard users' cookies and storage. Otherwise your %LOCALAPPDATA%\SwingWebView default applies.
• Older native libraries now give a failed future instead of a synchronous UnsatisfiedLinkError.
• New demo: demos/WebViewCookieDemo with run-{linux,mac}-cookie-demo.sh / run-windows-cookie-demo.bat. It passes on macOS, Windows and Linux.

Thanks again for the contribution!

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