fix(storage): prevent event loss during conversation moves (#361)

Ensure that conversation events are eagerly loaded from disk before the
storage layer deletes an old conversation directory during a move or
rename operation.

Previously, because events are loaded lazily, if a conversation was
modified (e.g., toggling `--local` or changing the title) without being
active, its event stream remained uninitialized in memory. The
persistence logic would then delete the old directory and skip writing
`events.json` to the new location because the in-memory buffer was
empty, resulting in total loss of the conversation's history.

The `Storage` layer now checks if a modified or active conversation has
missing events in memory and attempts to load them from the old path
before proceeding with the directory cleanup and write cycle.

Signed-off-by: Jean Mertz <[email protected]>

Author: JeanMertz