Accept theirs for conflicting lock files instead of deleting them

Removing lock files during conflict resolution caused missing dependencies
after the merge. Checking out theirs and staging preserves a valid lockfile.

src/commands/helpers.ts

@@ -81,7 +81,7 @@ export async function teardownSession(root: string, branch: string, worktree: st
   await state.removeSession(root, branch)
 }
 
-/** Files that should be removed rather than resolved — they get regenerated. */
+/** Lock files to skip AI resolution — accept theirs and move on (basename match covers subdirs too). */
 const SKIP_RESOLVE = new Set(["bun.lock", "Cargo.lock"])
 
 /** Resolve conflict markers in files using Claude, then stage them. */
@@ -95,7 +95,11 @@ export async function resolveConflicts(
     onFile(file, i + 1, files.length)
 
     if (SKIP_RESOLVE.has(basename(file))) {
-      await $`git rm -f -- ${file}`.cwd(cwd).nothrow().quiet()
+      const result = await $`git checkout --theirs -- ${file}`.cwd(cwd).nothrow().quiet()
+      if (result.exitCode !== 0) {
+        throw new Error(`Failed to resolve lock file ${file}: ${result.stderr.toString().trim()}`)
+      }
+      await git.stageFile(file, cwd)
       continue
     }