.commitmsg

feat: support Amazon DSP content URL on bid requests

Amazon DSP now requires in-app bid requests to carry the public web URL of the
content being viewed, so AmazonAdBot can crawl the page and verify what
surrounds the ad. Inventory it cannot verify progressively loses eligibility
with Amazon advertisers.

Adds an optional `contentUrl` to AdLoaderOptions, applied per bid request.

iOS: forwarded to +[APS setContentUrl:], called immediately before loadAd and
inside the same native method. That setter is a class method, so the value is
process-global; setting it there means another slot cannot overwrite it between
the two, since React Native serialises module methods on a single queue. An
empty value is skipped rather than forwarded — the SDK header states it throws
an NSException in development builds otherwise.

Android: ignored, and documented as such. The Android APS SDK
(com.amazon.android:aps-sdk 11.1.1) exposes no equivalent of setContentUrl —
verified against every public member of AdRegistration and DTBAdRequest.
Rejecting the promise would break the bidding chain for callers that
legitimately pass the option for iOS, so the option is accepted and dropped.

Two known limitations are documented in the README and have been raised with
Amazon APS: the Android gap above, and the fact that the iOS setter is sticky —
it cannot be cleared, so the last URL set stays attached to later requests until
another one replaces it.

Validation rejects a non-string contentUrl, consistent with the other options.
36 tests green.