feat(sceneRename): rename via moveFiles and record original filename

[stashdbcorrode248]

SceneRename renamed files with os.rename() behind Stash's back, then ran metadata_scan() on the parent folder to repair the database afterwards. The file record pointed at a stale path until that scan completed, and a full folder scan is heavy for a single-file change.

This switches the rename to the moveFiles mutation, so Stash moves the file and updates the file record in one transaction and no rescan is needed. A destination folder is required even for an in-place rename, so the file's current parent_folder id is passed, falling back to its path.

Other changes

• Require a title, not just a studio. Without one the filename collapsed to the studio plus resolution, which is less useful than the original name. The README already documented this requirement; the code now matches it. The skip message names the missing field rather than listing every field.
• Record the pre-rename basename in the scene's original_filename custom field, written once so the earliest known name survives later renames. A failed write logs a warning and does not fail the rename.
• Harden filename sanitising.: is now stripped from studio names and codes, which never passed through clean_title(); control characters are collapsed to spaces; leading dots and trailing dots/spaces are trimmed.
• Truncate to a byte budget rather than a character count. Filesystem name limits are in bytes (255 on ext4/btrfs), so a 240-character non-ASCII title could produce a name well over the limit and fail to rename. The budget also reserves room for the extension and a duplicate suffix.
• Correct the README format string and worked example, which showed the resolution before the title while form_filename() emits it after.

Version bumped to 1.2.0.

Testing

Run against a live Stash 0.31.1 library. Renames land through moveFiles with no rescan and no stale paths; original_filename is populated; scenes missing a title are skipped with the field named in the log. Sanitising was checked against studio/title combinations containing colons, newlines, tabs, NUL, leading dots and trailing dots/spaces, plus a 300-character CJK title, which previously produced a 706-byte name and now stays within the 255-byte limit.

[discourse-stashapp]

This pull request has been mentioned on Stash Forum. There might be relevant details there:

https://discourse.stashapp.cc/t/scenerename/5795/4