Adds validate_public_request to the BooruClient event_hooks list so
every request (and every redirect hop) is checked against the block
list from _safety.py. Danbooru, Gelbooru, and Moebooru subclasses
all go through BooruClient.client and inherit the protection.
Preserves the existing _log_request hook by listing both hooks in
order: validate first (so blocked hops never reach the log), then
log.
Audit-Ref: SECURITY_AUDIT.md finding #1
Severity: High
pax
6eebb77ae5