Add rename history with undo

- New crates/renamr-core/src/history module: HistoryBatch/HistoryEntry
  records, revert_batch() moves files back to their original paths
  (skip-on-conflict, same policy as rename::execute_renames; recreates a
  deleted destination folder defensively), push_batch() maintains a
  most-recent-first log capped at 50 batches. A partial port of the idea
  behind net.filebot.HistoryDialog, as a flat undo stack rather than a full
  session/element log. 6 new tests.
- New src-tauri/src/history.rs: persists the log as history.json in the OS
  app-config directory (same location as settings.json). execute_rename now
  takes an AppHandle and calls history::record_batch after every rename,
  recording only the items that actually got renamed. Two new commands:
  list_rename_history and undo_rename_batch.
- Frontend: the History button (previously a no-op) now opens a panel
  listing past rename batches with a timestamp, file count, and the
  old-name/new-name pairs, each with an Undo button. Undoing reconciles any
  currently-loaded item back to its pre-rename path/name, same pattern as
  post-rename reconciliation.
- Verified via cargo test (45 total)/check + npm build + a full Playwright
  pass: loaded mocked files, renamed them, opened History, undid the batch,
  and confirmed both the UI and the (mocked) backend state matched at every
  step.

README.md

@@ -10,10 +10,11 @@ detection ("Match") is working, real online metadata lookups against TMDB ("Fetc
 Data") are working — including fuzzy show-name disambiguation, so a search that
 returns several similarly-named shows doesn't just take TMDB's top-ranked hit — and the
 actual on-disk rename operation is wired up (skip-on-conflict, with a confirmation step
-showing the full old-name/new-name plan before anything touches disk — there is no undo
-yet). Rename can also organize files into subfolders — including ones that don't exist
-yet — when the naming scheme includes a `/`. Full media-metadata bindings are not yet
-ported. See "Porting roadmap" below.
+showing the full old-path/new-path plan before anything touches disk). Rename can also
+organize files into subfolders — including ones that don't exist yet — when the naming
+scheme includes a `/`. Every completed rename is logged to a history panel that can
+undo it, moving files back to their original paths. Full media-metadata bindings are
+not yet ported. See "Porting roadmap" below.
 
 The naming scheme is fully user-editable from the app (the "Naming Scheme" button next
 to the New Names list) — the default is `{show name} - {season number}x{episode
@@ -110,23 +111,26 @@ crates/renamr-core/   Pure Rust core: naming-expression engine (ported), local
                        (`similarity/`, partial `EpisodeMetrics` port), a TMDB metadata
                        client (`web/tmdb.rs` — TV search + episode lookup, disambiguated
                        via `similarity/`, tested against a mocked HTTP server via
-                       `mockito`), and the on-disk rename engine (`rename/`) —
+                       `mockito`), the on-disk rename engine (`rename/`) —
                        skip-on-conflict, can also organize into (auto-created)
-                       subfolders when the naming scheme includes `/`. Not yet ported:
-                       full media metadata bindings, other web datasource clients
-                       (TVDB/AniDB/etc).
+                       subfolders when the naming scheme includes `/` — and a rename
+                       history/undo log (`history/`, a partial `HistoryDialog` port).
+                       Not yet ported: full media metadata bindings, other web
+                       datasource clients (TVDB/AniDB/etc).
                        No Tauri dependency, so it builds and unit-tests standalone.
 src-tauri/             Tauri app shell: exposes renamr-core as commands to the frontend
                        (naming-scheme rendering, filename matching, TMDB metadata fetch,
                        executing a rename plan, native file/folder dialogs, drag-and-drop
-                       expansion), plus `settings.rs` (TMDB token, stored as JSON in the
-                       OS app-config directory), app metadata/icons/window config
+                       expansion), plus `settings.rs` (TMDB token) and `history.rs`
+                       (rename history/undo log) — both stored as JSON in the OS
+                       app-config directory — app metadata/icons/window config
                        (tauri.conf.json).
 src/                   React + TypeScript UI (Vite). Faithful recreation of the original
                        two-pane rename screen (Aurora theme) wired to real file loading,
                        drag-and-drop, live naming-scheme preview, local matching, TMDB
-                       fetch (behind a Settings modal for the API token), and a
-                       confirm-before-touching-disk modal for the actual rename.
+                       fetch (behind a Settings modal for the API token), a
+                       confirm-before-touching-disk modal for the actual rename, and a
+                       History panel that can undo a past rename.
 scripts/gen_icons.py   Regenerates src-tauri/icons/ (placeholder branding — swap the
                        colors/glyph in the script, or replace the icons directly, to
                        change the look).
@@ -217,13 +221,18 @@ ported from, for anyone picking this up:
    `--conflict` variants beyond skip (auto-number, override), and the CLI flag surface
    itself.
 7. **The rest of the UI** — the Rename panel (file loading, drag-drop, live preview,
-   local matching, confirmed rename) is built; the other five sidebar panels
-   (Episodes/Subtitles/SFV/Filter/List) are still stub screens, plus Align up/down
-   reordering, History, and Presets on the Rename panel itself are no-ops. There's also
-   no per-item exclude inside the rename confirmation modal yet (it's all-or-nothing —
-   use "Exclude Selected" on the file list beforehand to leave a file out entirely).
-8. **Undo/history for renames** — there is no undo yet; the confirmation modal before
-   Rename executes is the only safety net right now. `net.filebot.HistoryDialog`/the
-   original's rename-history log is the reference for what a real undo would look like.
+   local matching, confirmed rename, rename history/undo) is built; the other five
+   sidebar panels (Episodes/Subtitles/SFV/Filter/List) are still stub screens, plus
+   Align up/down reordering and Presets on the Rename panel itself are still no-ops.
+   There's also no per-item exclude inside the rename confirmation modal yet (it's
+   all-or-nothing — use "Exclude Selected" on the file list beforehand to leave a file
+   out entirely).
+8. **Undo/history for renames** — done, as a flat JSON-backed undo stack rather than a
+   full port of `net.filebot.HistoryDialog`'s session/element log
+   (`crates/renamr-core/src/history`, `src-tauri/src/history.rs`). Every successful
+   rename is recorded to a `history.json` in the OS app-config directory (same location
+   as `settings.json`); the History panel lists past batches and can revert one back to
+   its original paths, skipping (never overwriting) any file whose original path now
+   has something else at it. Capped at the 50 most recent batches.
 9. **Packaging** — code signing, auto-update, installers per platform via
    `npm run tauri build`.