[P1-05] Add tool governance and approval policies

[erikhoward]

Goal

Make tool use policy-driven, auditable, and safe for untrusted workflow inputs.

Scope

• Add per-workflow and per-tenant tool allowlists/denylists.
• Classify dangerous or side-effecting tools and require approval when configured.
• Validate tool input/output schemas, timeout/concurrency budgets, and payload limits.
• Add audit records for tool discovery, invocation, approval, rejection, and failure.
• Integrate policy decisions with Guardian and durable human approval.

Acceptance criteria

• A workflow cannot invoke a tool outside its effective policy.
• Dangerous actions can be blocked or routed to human approval.
• Invalid tool payloads fail before invocation and are recorded safely.
• Audit records are tenant-scoped, queryable, and redacted.

Priority

P1 — high-value security and operations enhancement.

See the PetalFlow 1.0.0 Readiness Report for the audit context.