Per-URL ask/deny rules for artifact reads, page-data reads, diagnostics, and database reads

Artifact tool permission checks gain a new rule-matching step that checks configured deny/ask rules against the specific artifact URL before falling back to session-wide consent. This covers the read_page_data, verify (diagnostics), read, and read_db actions, and permission messages now surface which rule matched, for example when Claude wants to read the structured page data of an artifact.