feat(client): sync --force to escape the locally-modified skip

Managed items with local modifications were kept (skip + warn) with no
escape hatch other than deleting the deployed file by hand — after an
upstream change the deployed content silently stayed old, which reads
exactly like a stale cache.

--force turns the two skip cases into update (repository version wins)
and remove (upstream deleted + modified). Unmanaged items and never-
managed path occupancies stay untouched even with --force; the default
behavior is unchanged.

internal/e2e/sync_force_test.go

@@ -0,0 +1,83 @@
+package e2e
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+// TestSyncForceOverwritesLocallyModified pins the --force escape hatch:
+// locally modified managed items are overwritten with the repository
+// version, upstream-deleted modified items are removed, and unmanaged
+// local items are never touched.
+func TestSyncForceOverwritesLocallyModified(t *testing.T) {
+	h := newHarness(t)
+	env := newSyncEnv(t, h)
+	buildWorkRepo(t, h, env.workRepo)
+	env.writeConfig(t, env.workRepo, "")
+	env.run(t)
+
+	// local drift on a managed item + upstream change to the same item
+	deployed := filepath.Join(env.home, ".config/opencode/commands/deploy.md")
+	os.WriteFile(deployed, []byte("---\nname: Deploy\n---\nlocal drift\n"), 0o644)
+	upstream := filepath.Join(env.workRepo, "commands/deploy.md")
+	os.WriteFile(upstream, []byte("---\nname: Deploy\ndescription: updated\n---\nnew body\n"), 0o644)
+
+	// an unmanaged local item that must survive --force untouched
+	unmanaged := filepath.Join(env.home, ".config/opencode/commands/mine.md")
+	os.MkdirAll(filepath.Dir(unmanaged), 0o755)
+	os.WriteFile(unmanaged, []byte("---\nname: Mine\n---\nprecious\n"), 0o644)
+
+	h.git(t, env.workRepo, "add", "-A")
+	h.git(t, env.workRepo, "commit", "-m", "update deploy command")
+
+	out, err := env.run(t)
+	if err != nil {
+		t.Fatalf("sync failed: %v\n%s", err, out)
+	}
+	if !contains(out, "skipped (local modifications kept): 1") {
+		t.Errorf("default sync must keep the local modification:\n%s", out)
+	}
+
+	out, err = env.run(t, "--force")
+	if err != nil {
+		t.Fatalf("sync --force failed: %v\n%s", err, out)
+	}
+	if !contains(out, "updated:  1") {
+		t.Errorf("force must update the locally modified item:\n%s", out)
+	}
+	if got := readFile(t, deployed); !contains(got, "new body") {
+		t.Error("force must overwrite the local drift with the repository version")
+	}
+	if got := readFile(t, unmanaged); !contains(got, "precious") {
+		t.Error("force must never touch unmanaged local items")
+	}
+
+	// upstream deletion of a locally modified item: force removes it
+	os.WriteFile(deployed, []byte("---\nname: Deploy\n---\nmore drift\n"), 0o644)
+	os.Remove(upstream)
+	h.git(t, env.workRepo, "add", "-A")
+	h.git(t, env.workRepo, "commit", "-m", "delete deploy command")
+
+	out, err = env.run(t)
+	if err != nil {
+		t.Fatalf("sync failed: %v\n%s", err, out)
+	}
+	if !contains(out, "skipped (local modifications kept): 1") {
+		t.Errorf("default sync must keep the modified item after upstream deletion:\n%s", out)
+	}
+	if _, err := os.Stat(deployed); err != nil {
+		t.Fatal("item must still exist before force")
+	}
+
+	out, err = env.run(t, "--force")
+	if err != nil {
+		t.Fatalf("sync --force failed: %v\n%s", err, out)
+	}
+	if !contains(out, "removed:  1") {
+		t.Errorf("force must remove the locally modified item after upstream deletion:\n%s", out)
+	}
+	if _, err := os.Stat(deployed); !os.IsNotExist(err) {
+		t.Error("forced removal must delete the deployed file")
+	}
+}