Reviewer caught (correctly) that the #3506 text fallback relied on
`clipboard.readText()`, which on Darwin shells out to `pbpaste(1)` —
pbpaste only surfaces plain text / RTF / EPS, so a Finder Cmd+C
pasteboard (`public.file-url` only, no plain text, no raw image bytes)
made readText() return empty and the new path-detection never ran.
Add a Darwin-only `readMacFileUrlsFromClipboard` helper that pipes a
small AppleScript through `osascript -` to coerce the pasteboard via
`«class furl»` and emit POSIX paths one per line. Wire it into
`InputController.handleImagePaste` between the readImage and readText
calls; the first image-shaped path routes through
`handleImagePathPaste`, non-image file URLs (e.g. a copied .pdf) fall
through to the existing text fallback. The clipboard interface field is
optional so existing test fixtures keep working without changes.
Tests: covers (a) Darwin file-URL pasteboard with empty pbpaste,
(b) non-image file URLs falling through to text, (c) the helper itself
on darwin/non-darwin and when osascript fails.
Refs #3506
roboomp
b3f99dc634