Rename quack to quak

German for 'quack', matching the Ente (German for 'duck') naming. All
references updated: package name, CLI binary, X-Client-Package header,
test descriptions, temp dir prefixes, README, Makefile docker tag.

test/api/client.test.ts

@@ -1,7 +1,7 @@
 /**
  * Tests for `ApiClient`.
  *
- * `ApiClient` is the HTTP layer that every other module in quack calls to
+ * `ApiClient` is the HTTP layer that every other module in quak calls to
  * reach the Ente server. It handles:
  *
  *   - Base URL resolution. Production uses `https://api.ente.io` for the
@@ -14,7 +14,7 @@
  *     dedicated CDN hosts.
  *
  *   - Required headers. Every request carries `X-Client-Package`
- *     (`berlin.sneak.quack`). Authenticated requests also carry
+ *     (`berlin.sneak.quak`). Authenticated requests also carry
  *     `X-Auth-Token` with the token recovered by `unwrapAuth`.
  *
  *   - JSON serialization. `getJSON` and `postJSON` handle Accept /
@@ -121,7 +121,7 @@ describe("ApiClient defaults", () => {
         await client.getJSON("/ping");
 
         const headers = new Headers(calls[0]!.init?.headers as HeadersInit);
-        expect(headers.get("X-Client-Package")).toBe("berlin.sneak.quack");
+        expect(headers.get("X-Client-Package")).toBe("berlin.sneak.quak");
     });
 });