Replace the pending-actions preview flow with immediate execution and
undo support. ToolExecutor now accepts an UndoManager and records
create, modify, rename, and trash operations so users can roll back
batches.
Other fixes included:
- Deep-merge nested config objects on settings load to preserve new
default fields
- Increase retry backoff from 10ms to 1000ms and widen the "invalid
response format" check to handle prefixed messages
- Fix semantic cache clear to null out the collection reference
- Tighten memory regex to require "please always/never"
- Increase vault indexing batch size from 1 to 5
- Remove unused modeRequiresPreview helper
