fix: create destination directory when moving a note

[postoso]

Description

move now creates any missing directories in the destination path before renaming the file, so notesmd-cli move "Target Note" "newfolder/Target Note" works without running mkdir first.

(*Note).Move called os.Rename and mapped every error to NoteDoesNotExistError. os.Rename returns ENOENT when the destination directory is missing, so the command printed "Cannot find note in vault" and blamed a source note that was sitting right there. The source is now checked before the directory is created, so a genuinely missing note still reports NoteDoesNotExistError and does not leave an empty destination folder behind on its way to failing.

Motivation and Context

Fixes #134.

That issue offered two options, better error text or creating the folder, and asked which you preferred. I went with creating it because create and daily already do exactly this for their note paths (pkg/actions/create.go:43, pkg/actions/daily.go:47), which left move as the odd one out. If you would rather move stay conservative and just report the missing folder, say so and I will swap the os.MkdirAll for a check on the parent directory plus a new error constant. It is a small change either way.

Two subtests added to TestMoveNote: one moves a note into a nested path that does not exist yet, one checks that a missing source note fails without creating the destination directory. The first fails on unpatched note.go with the exact error from the issue.

The README line for move gains the same sentence the create section already has about intermediate directories.

Checklist:

• I have written unit tests for my changes.
• I have updated the documentation accordingly.
• All new and existing tests passed.

[Yakitrak]

LGTM, thats for the PR!