Add campaign-level negative keywords

Blocks queries from triggering ads anywhere in one campaign. Negatives that already exist are skipped, and the result lists them. Use when: google_analyze_search_terms found wasted queries and the user has approved the list. Do not use when: the term also appears in queries that converted — blocking it costs real conversions. Show the user the list and get an explicit yes first. Match types work differently for negatives than for normal keywords: a broad negative blocks queries containing all of its words in any order, a phrase negative blocks queries containing the words in that order, and an exact negative blocks only that precise query. Negatives never expand to synonyms or close variants, so plurals and misspellings need their own entries. Adding a negative is reversible with google_remove_negative_keywords, but removal is permanent, so prefer adding fewer, well-understood negatives. If you are unsure which account, campaign or period the user means, ask them — do not guess ids or dates.