Add CSV mapping rule and Undo last rename feature

Made-with: Cursor

README.md

@@ -13,7 +13,9 @@ A **native Linux** GUI for mass renaming files. Inspired by [Bulk Rename Utility
 - **Case** – Title Case, UPPER, lower, Sentence case.
 - **Numbering** – Add a running number (prefix/suffix/insert) with start, step, and padding.
 - **Prefix / Suffix** – Add fixed text to the beginning or end of every name.
+- **CSV mapping** – Rename from a CSV with columns **Original Name** and **Target Name** (one row per file; lookup by current filename).
 - **Safe renames** – Two-pass rename to avoid overwrites; collision detection in preview.
+- **Undo** – After applying renames, use **Undo last rename** in the same folder to revert (undo log is stored as a hidden file in that folder).
 
 ## Requirements
 
@@ -53,6 +55,13 @@ python main.py
 
 Sort order is the current list order (alphabetical by filename). Reorder files in the table (e.g. by dragging) if you add that later; for now, use the order given after opening the folder.
 
+### CSV mapping
+
+1. Create a CSV with header row: **Original Name**, **Target Name**.
+2. One data row per file: first column = current filename, second column = desired new name.
+3. Enable **9. CSV mapping**, click **Browse…** and select the CSV.
+4. Only rows that match a current filename in the folder are renamed; others are unchanged. You can combine with other rules (CSV is applied in rule order).
+
 ## AppImage (distribution)
 
 To build a portable AppImage: