Add Handy / Funscript support (#1377)

* Add funscript route to scenes

Adds a /scene/:id/funscript route which serves a funscript file, if present.

Current convention is that these are files stored with the same path, but with the extension ".funscript".

* Look for funscript during scan

This is stored in the Scene record and used to drive UI changes for funscript support.

Currently, that's limited to a funscript link in the Scene's file info.

* Add filtering and sorting for interactive
* Add Handy connection key to interface config
* Add Handy client and placeholder component.

Uses defucilis/thehandy, but not thehandy-react as I had difficulty integrating the context with the existing components.

Instead, the expensive calculation for the server time offset is put in localStorage for reuse.

A debounce was added when scrubbing the video, as otherwise it spammed the Handy API with updates to the current offset.

pkg/utils/file.go

@@ -296,3 +296,11 @@ func GetNameFromPath(path string, stripExtension bool) string {
 	}
 	return fn
 }
+
+// GetFunscriptPath returns the path of a file
+// with the extension changed to .funscript
+func GetFunscriptPath(path string) string {
+	ext := filepath.Ext(path)
+	fn := strings.TrimSuffix(path, ext)
+	return fn + ".funscript"
+}