Contributing Windows Support to Tailscale Browser Extension

I contributed two PRs to tailscale/ts-browser-ext, the native messaging backend that powers the Tailscale browser extension for Chrome and Firefox.

PR #16 — Windows Support

The extension previously only worked on Linux and macOS. This PR adds full Windows support:

Registry-based native messaging — On Windows, Chrome and Firefox discover native messaging hosts via registry keys under HKCU, not filesystem paths. Added registry_windows.go to create/delete the correct keys under Software\Google\Chrome\NativeMessagingHosts and Software\Mozilla\NativeMessagingHosts.
Platform-specific syslog — log/syslog doesn’t exist on Windows. Extracted the syslog setup into syslog_other.go (unix/darwin) and syslog_windows.go (no-op), so the binary compiles cleanly on all platforms.
Binary naming — Windows needs .exe suffix. Added a binaryName() helper used by both install() and uninstall().
JSON path fix — Used filepath.ToSlash so the path field in the native messaging JSON manifest uses forward slashes, which Chrome and Firefox accept on Windows.
Popup login fix — The “Log in” link in the popup was a dead #login href. Now it actually opens the auth URL via chrome.tabs.create.

The project was pinned to Tailscale v1.80.1 and Go 1.23.4. This PR bumps them:

Tailscale v1.80.1 to v1.96.5 — Picks up all upstream improvements and fixes.
Go 1.23.4 to 1.26.1 — Moves to the latest stable Go release.
Import path migration — The local API client moved from tailscale.com/client/tailscale to tailscale.com/client/local, so updated the import and IPNBusWatcher type references accordingly.

Both PRs are currently open and under review.