Implement editor atomic save coalescing and snapshot storm prevention

[barissalihbabacan]

Context

Modern creative editors (Photoshop, Blender, VS Code, Figma local) frequently perform atomic saves by writing to temporary files (e.g. file.tmp), renaming to target, and deleting old files within milliseconds.

Proposed Solution

• Filter transient/intermediate editor files (e.g. ~*, *.tmp, .DS_Store).
• Coalesce rename and write events into a single snapshot trigger.
• Enforce minimum inter-snapshot cooldown to prevent snapshot storms during rapid saves.