Add undo/redo stack for tag operations (assign, remove, rename, merge) with Ctrl+Z/Ctrl+Y

CHANGELOG.md

@@ -2,6 +2,46 @@
 
 All notable changes to the Tagger project are documented in this file.
 
+## [1.2.0] - 2026-04-09
+
+### Added
+- **Undo/redo** - `Ctrl+Z` / `Ctrl+Y` vrátí/zopakuje tag operace (assign, remove, rename, merge)
+  - Zásobník 50 kroků, čistí se při zavření složky
+  - Edit menu zobrazuje popis poslední operace
+  - Pokrývá: přiřazení tagu, odebrání tagu, přejmenování tagu/kategorie, sloučení tagu/kategorie
+- **CSFD cache** - Movie data cached in `.!tag` after first fetch, no re-fetching on reopen
+  - `CSFDMovie.to_dict()` / `from_dict()` for serialization
+  - `File.get_cached_movie()` - returns cached data without network access
+  - Cache versioning (`CSFD_CACHE_VERSION`) for future schema invalidation
+  - Cache invalidated automatically when CSFD URL changes
+- **Orphaned sidecar detection** - On folder scan, `.!tag` files without a matching media file are reported
+  - `FileManager.on_orphaned_tags` callback for UI notification
+  - `FileManager.find_orphaned_tags()` for manual scan
+- **OR/NOT tag filtering** - Extended `filter_files_by_tags()` with new parameters
+  - `any_of` - file must have at least one of these tags (OR)
+  - `must_not` - file must not have any of these tags (NOT)
+  - Fully backward compatible
+- **ffprobe threading** - Video resolution detection now runs in background (`VideoResolutionWorker`)
+  - Status bar shows live progress: `Zjišťuji rozlišení (3/12)…`
+  - Menu action disabled during processing
+- **Export to CSV** - Soubor → "Exportovat do CSV..."
+  - UTF-8 BOM encoding (Excel compatible)
+  - Columns: filename, path, date, tags, CSFD URL, size
+- **Drag & drop** - Drag folder or file onto the app window to open it
+
+### Changed
+- **Global config location** - Moved from app directory to `~/.config/Tagger/`
+  - Automatic one-time migration from old location
+  - Fixes crash on read-only PyInstaller build directories
+- **Python version** - Bumped to 3.14+
+
+### Dependencies
+- Removed: Pillow (unused)
+- Moved: python-dotenv from dev to runtime dependencies
+
+### Tests
+- 274 tests (all passing)
+
 ## [1.1.0] - 2026-01-23
 
 ### Changed