fix: bound Homebrew cleanup failure feedback

src/lib/BrewCleanup.svelte

@@ -25,8 +25,8 @@
     reset();
     try {
       judgment = await api.judgeBrewCleanup();
-    } catch (e) {
-      error = String(e);
+    } catch {
+      error = "Homebrew 정리 계획을 만들지 못했습니다.";
     } finally {
       planning = false;
     }
@@ -72,8 +72,8 @@
         confirmationPhrase.trim(),
         rationale.trim(),
       );
-    } catch (e) {
-      error = String(e);
+    } catch {
+      error = "Homebrew 정리를 실행하지 못했습니다.";
     } finally {
       judgment = null;
       confirmationPhrase = "";

src/lib/brewCleanupErrorPrivacyContract.test.ts

@@ -0,0 +1,30 @@
+import { readFileSync } from "node:fs";
+import { dirname, resolve } from "node:path";
+import { fileURLToPath } from "node:url";
+import { describe, expect, it } from "vitest";
+
+const repositoryRoot = resolve(dirname(fileURLToPath(import.meta.url)), "../..");
+
+function readSource(path: string): string {
+  return readFileSync(resolve(repositoryRoot, path), "utf8");
+}
+
+describe("BrewCleanup privacy-safe failure feedback", () => {
+  it("never renders arbitrary backend exception text", () => {
+    const source = readSource("src/lib/BrewCleanup.svelte");
+
+    expect(source).not.toContain("String(e)");
+    expect(source).toContain("Homebrew 정리 계획을 만들지 못했습니다.");
+    expect(source).toContain("Homebrew 정리를 실행하지 못했습니다.");
+    expect(source).toContain('role="alert"');
+  });
+
+  it("preserves the existing judgment and execution authority calls", () => {
+    const source = readSource("src/lib/BrewCleanup.svelte");
+
+    expect(source).toContain("api.judgeBrewCleanup()");
+    expect(source).toContain("api.executeBrewCleanup(");
+    expect(source).toContain("submittedJudgment.plan_fingerprint");
+    expect(source).toContain("submittedJudgment.judgment_id");
+  });
+});