fix: preserve recent captures across saves and editor handoffs

[tusharmalpani20]

Recent captures can lose edits or reference the wrong working document when autosave, output, reopening, and editor handoffs overlap.

Publish recent entries only after their source image and operation log are ready. Preserve the existing document when publication fails and remove a replaced entry only after its replacement succeeds.

Also:

• Prevent stale autosave results from replacing the current document's source.
• Preserve original pixels so reopening does not apply cuts twice.
• Finish pending document writes safely during shutdown.
• Preserve recent-entry identity through window-selection handoffs.
• Open recent captures for editing from the initial capture screen.
• Prevent output from racing unfinished edits.

Keep persistence work off the UI thread.

Validation:

• Full headless smoke suite and affected clang-tidy checks passed.
• Covered publication failure and retry, stale autosaves, reopening, full-shelf replacement, shutdown, and valid and invalid handoffs.