Sync Content on Initial Pull

• Fix: pulling a post that has never been transferred no longer fails outright when the target environment already has a matching item (same type + slug, or same post id) — the pull now adopts it and links the two, the same way a first push already did on its receiving end. Previously, only pushing could establish that first link, which meant content created directly in an environment that has no Push button (production) could never be pulled elsewhere.
• Add "Sync new from…" to the Posts/Pages/CPT list screens: scans the chosen environment for content of that type this site doesn't have a linked copy of yet, and lets you pick which of it to pull in as new drafts (or link to a matching existing item) — for the case where content originates on an environment you can only pull from, not push to.