Guardrails: Inline validator support #1247

Is your feature request related to a problem?
Guardrail entries in an LLM config blob (input_guardrails / output_guardrails) can only reference a validator_config_id saved in the guardrails service. A validator cannot be defined directly in the config, and the only way to turn one off is to delete it from the config version, which loses its setup.

Describe the solution you'd like

• Let each guardrail entry be either a validator_config_id reference or an inline validator spec (type, on_fail, per-type params).
• Restrict inline type to gender_assumption_bias, pii_remover, profanity_free, topic_relevance_llm for now.
• Add an is_enabled flag (default true) to both entry kinds. Disabled entries stay saved in the config version but are never fetched or sent to the guardrails service.
• Send validators to the guardrails service in config order. Stamp stage on inline specs and strip is_enabled, since the service's validator schemas forbid extra fields.

Comments: Implemented in #1245.