fix: add --prune and --json to KNOWN_FLAGS for spawn status (#2263)

The status command (PR #2254) added --prune and --json flags but did not
register them in KNOWN_FLAGS. This caused the CLI to reject them with
"Unknown flag" errors before the command could even dispatch.

Bump CLI version 0.15.4 -> 0.15.5.

Agent: ux-engineer

Co-authored-by: B <6723574+louisgv@users.noreply.github.com>
Co-authored-by: Claude Sonnet 4.5 <noreply@anthropic.com>

packages/cli/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@openrouter/spawn",
-  "version": "0.15.4",
+  "version": "0.15.5",
   "type": "module",
   "bin": {
     "spawn": "cli.js"

packages/cli/src/__tests__/unknown-flags.test.ts

@@ -10,13 +10,13 @@ import { expandEqualsFlags, findUnknownFlag, KNOWN_FLAGS } from "../flags";
 
 describe("Unknown Flag Detection", () => {
   describe("detects unknown flags", () => {
-    it("should detect --json as unknown", () => {
+    it("should detect --foo as unknown", () => {
       expect(
         findUnknownFlag([
           "list",
-          "--json",
+          "--foo",
         ]),
-      ).toBe("--json");
+      ).toBe("--foo");
     });
 
     it("should detect --verbose as unknown (middle position)", () => {
@@ -50,20 +50,20 @@ describe("Unknown Flag Detection", () => {
     it("should detect unknown flag at the beginning", () => {
       expect(
         findUnknownFlag([
-          "--json",
+          "--foo",
           "list",
         ]),
-      ).toBe("--json");
+      ).toBe("--foo");
     });
 
     it("should return first unknown when multiple unknown flags", () => {
       expect(
         findUnknownFlag([
-          "--json",
+          "--foo",
           "--verbose",
           "list",
         ]),
-      ).toBe("--json");
+      ).toBe("--foo");
     });
   });
 
@@ -87,6 +87,8 @@ describe("Unknown Flag Detection", () => {
         "--debug",
         "--name",
         "--reauth",
+        "--prune",
+        "--json",
       ];
       for (const flag of knownFlagsToTest) {
         expect(
@@ -211,6 +213,8 @@ describe("KNOWN_FLAGS completeness", () => {
       "--clear",
       "--custom",
       "--reauth",
+      "--prune",
+      "--json",
     ];
     for (const flag of expected) {
       expect(KNOWN_FLAGS.has(flag)).toBe(true);

packages/cli/src/flags.ts

@@ -28,6 +28,8 @@ export const KNOWN_FLAGS = new Set([
   "--region",
   "--machine-type",
   "--size",
+  "--prune",
+  "--json",
 ]);
 
 /** Return the first unknown flag in args, or null if all are known/positional */