WSDL gap

Issue #239 optional-field audit confirms AdGroupAddItem.NegativeKeywords, AdGroupUpdateItem.NegativeKeywords, AdGroupAddItem.NegativeKeywordSharedSetIds, and AdGroupUpdateItem.NegativeKeywordSharedSetIds are WSDL-supported optional fields. The CLI currently exposes shared negative keyword set management as its own resource, but ad-group-level add/update has no typed flags for these fields.

Expected CLI contract

• Add explicit comma-separated/list flags for ad-group negative keywords and shared-set IDs on direct adgroups add/update.
• Keep inputs typed; do not forward raw JSON or nested blobs.
• Add dry-run payload tests and WSDL/audit coverage.

Verification

• direct adgroups add --name G --campaign-id 1 --region-ids 225 --negative-keywords word1,word2 --dry-run
• direct adgroups update --id 1 --negative-keyword-shared-set-ids 10,11 --dry-run

Refs: #239.