quak login --server: log in to a self-hosted Ente server (closes #243)

`quak login` takes the server's API address from `--server` or
`QUAK_SERVER`, refusing anything that is not an http or https URL. The
client's snapshot now keeps a non-default `apiOrigin`, so the session
file names the server and every later command uses it. A snapshot's
`apiOrigin` wins over the one in `fromJSON`'s `apiOptions`, since the
token belongs to that server.

Model: opus-5-5

test/cli/bin.test.ts

@@ -2,8 +2,9 @@
  * Tests for the retry options `bin/quak.ts` loads the saved session with
  * (`quak backup` gets the unattended ones, every other command the default),
  * each with the callbacks that log its requests and retries, for `quak files`
- * taking its collection ID as an optional argument, and for `quak get` and
- * `quak get-thumb` refusing `--collection`.
+ * taking its collection ID as an optional argument, for `quak get` and
+ * `quak get-thumb` refusing `--collection`, and for `quak login` taking
+ * `--server`.
  *
  * Each test runs `bin/quak.ts`, as the smoke test does, with its session loader
  * replaced by one that records the options it is given and reports no session,
@@ -117,3 +118,13 @@ describe("bin/quak.ts get and get-thumb", () => {
         },
     );
 });
+
+// The command refuses an address that is not a URL before it asks for anything
+// or sends any request.
+describe("bin/quak.ts login", () => {
+    it("hands --server to the command", async () => {
+        expect(await quak("login", "--server", "ente.example.com")).toMatch(
+            /^Invalid server address "ente\.example\.com"/,
+        );
+    });
+});