feat(data): add x-firefox-ai default challenge rule (#580)

Signed-off-by: Xe Iaso <me@xeiaso.net>

data/botPolicies.yaml

@@ -30,6 +30,8 @@ bots:
   #   - Marginalia
   #   - Mojeek
   - import: (data)/crawlers/_allow-good.yaml
+  # Challenge Firefox AI previews
+  - import: (data)/clients/x-firefox-ai.yaml
 
   # Allow common "keeping the internet working" routes (well-known, favicon, robots.txt)
   - import: (data)/common/keep-internet-working.yaml

data/clients/x-firefox-ai.yaml

@@ -0,0 +1,4 @@
+# https://connect.mozilla.org/t5/firefox-labs/try-out-link-previews-in-firefox-labs-138-and-share-your/td-p/92012
+- name: x-firefox-ai
+  action: CHALLENGE
+  expression: '"X-Firefox-Ai" in headers'