feat: change --timeout from milliseconds to seconds

Accept seconds (including decimals like 0.5) instead of milliseconds
for the --timeout flag. Converts to ms internally. Default is now 10
(seconds) instead of 10000. Error messages display seconds.

Update AGENTS.md, tests, and skill docs to match.

test/smoke.js

@@ -254,7 +254,7 @@ test(
 
     assert.equal(output.ok, false);
     assert.equal(output.error.code, "INVALID_OPTION");
-    assert.match(output.error.message, /--timeout must be a positive integer/);
+    assert.match(output.error.message, /--timeout must be a positive number/);
     assert.equal(typeof output.elapsedMs, "number");
   },
 );
@@ -290,7 +290,7 @@ test("wait-js timeout returns wait timeout", ["wait", "errors"], () => {
     dataHtml("<title>Hello</title>"),
     "--no-reader",
     "--wait-js=return false",
-    "--timeout=1",
+    "--timeout=0.001",
   ]);
 
   assert.equal(output.ok, false);