Add conflict policy options: Skip / Auto-number / Override

New ConflictPolicy enum in rename/ (Skip = original/default behavior,
AutoNumber = save as "Name (1).ext" counting up to the first free slot,
Override = replace the conflicting file outright), threaded through
execute_renames/rename_one alongside RenameAction. Override never deletes
a conflicting directory (falls back to Skip for that case); AutoNumber
sidesteps directories the same way by just trying the next number.
execute_rename now takes a conflict argument; undo/history are
deliberately NOT conflict-aware and always use their own fixed
skip-on-conflict policy regardless of what the original rename used.

Frontend: a second segmented selector in the rename confirmation modal
("On conflict: Skip / Auto-number / Override"), with Override styled in
red and its warning copy calling out that it can't be undone.

src/components/RenamePanel.tsx

@@ -98,6 +98,12 @@ interface RenameResult {
 // confirmRename below).
 type RenameAction = "move" | "copy" | "symlink";
 
+// Mirrors renamr-core's `ConflictPolicy` - what happens when a computed target already
+// exists. "skip" (the default, and the only behavior Renamr had before) leaves the
+// conflicting file alone; "autoNumber" saves alongside it as "Name (1).ext" instead;
+// "override" replaces it outright (irreversible for whatever gets overwritten).
+type ConflictPolicy = "skip" | "autoNumber" | "override";
+
 // Sent to `fetch_metadata`: one file's local guess (from Match) to resolve against
 // real TMDB data. Needs a series name + season/episode to search with - exactly what
 // Match already produces offline, which is why Fetch Data requires Match to have run
@@ -287,6 +293,25 @@ const RENAME_ACTION_LABELS: Record<
   },
 };
 
+// Copy for each ConflictPolicy, used in the confirmation modal's second segmented
+// selector and the modal's conflict-behavior note.
+const CONFLICT_POLICY_LABELS: Record<ConflictPolicy, { button: string; description: string }> = {
+  skip: {
+    button: "Skip",
+    description: "If a computed name already exists on disk, that file is left alone and skipped.",
+  },
+  autoNumber: {
+    button: "Auto-number",
+    description:
+      'If a computed name already exists on disk, the new one is saved alongside it as "Name (1).ext" instead (counting up until a free name is found).',
+  },
+  override: {
+    button: "Override",
+    description:
+      "If a computed name already exists on disk, it's replaced outright. This can't be undone — undoing this batch later can restore the source file, but not whatever got overwritten.",
+  },
+};
+
 function realFileToItem(entry: FileEntry): Item {
   return {
     id: entry.path,
@@ -372,6 +397,10 @@ export default function RenamePanel() {
   // remembered across modal opens within the session (defaults to "move", matching
   // Renamr's original and only behavior before copy/symlink existed).
   const [renameAction, setRenameAction] = useState<RenameAction>("move");
+  // What to do when a computed target already exists - same remembered-across-opens
+  // pattern as renameAction, defaults to "skip" (Renamr's original and only behavior
+  // before auto-number/override existed).
+  const [conflictPolicy, setConflictPolicy] = useState<ConflictPolicy>("skip");
   // TMDB token state for "Fetch Data". `null` = not checked yet, `false` = checked and
   // nothing saved, `true` = a token is on file (the value itself never comes back to
   // the frontend after saving - see Settings modal below).
@@ -707,6 +736,7 @@ export default function RenamePanel() {
       const results = await invoke<RenameResult[]>("execute_rename", {
         items: renamePlan.map((p) => ({ source: p.source, newName: p.newName })),
         action: renameAction,
+        conflict: conflictPolicy,
       });
       const bySource = new Map(results.map((r) => [r.source, r] as const));
       // Compute counts from `results` directly, not inside the setItems updater below:
@@ -1316,6 +1346,26 @@ export default function RenamePanel() {
                 </button>
               ))}
             </div>
+            <span className="modal-field-label">On conflict</span>
+            <div
+              className="action-segmented"
+              role="radiogroup"
+              aria-label="What to do when the computed name already exists"
+            >
+              {(["skip", "autoNumber", "override"] as const).map((c) => (
+                <button
+                  key={c}
+                  type="button"
+                  className={`action-segmented-option${conflictPolicy === c ? " selected" : ""}${
+                    c === "override" ? " action-segmented-option-danger" : ""
+                  }`}
+                  onClick={() => setConflictPolicy(c)}
+                  disabled={renaming}
+                >
+                  {CONFLICT_POLICY_LABELS[c].button}
+                </button>
+              ))}
+            </div>
             <p className="modal-subtitle">
               This will {RENAME_ACTION_LABELS[renameAction].verb} {renamePlan.length} file
               {renamePlan.length === 1 ? "" : "s"} on disk right now. Review the list below before continuing — use
@@ -1355,8 +1405,8 @@ export default function RenamePanel() {
                 ))
               )}
             </div>
-            <p className="modal-note">
-              If a computed name already exists on disk, that file is skipped rather than overwritten.
+            <p className={`modal-note${conflictPolicy === "override" ? " modal-note-danger" : ""}`}>
+              {CONFLICT_POLICY_LABELS[conflictPolicy].description}
             </p>
             <div className="modal-actions">
               <button className="action-button" onClick={cancelRename} disabled={renaming}>