[codex] Expand TrueFoundry skill workflows

[mnvsk97]

Summary

• add AI Gateway metrics recipes for cost, token, latency, and error questions
• clarify Skills Registry and Prompt Registry capability matrices and review gates
• add platform workflows for user invites, team/custom-role grants, PATs, VATs, and service-account caveats

Validation

• ./scripts/validate-skills.sh
• ./scripts/validate-skill-security.sh
• git diff --check

Notes

• Does not add or document tfy whoami; that CLI command is being handled separately.
• Keeps unsupported CLI surfaces such as tfy upload skill marked as unavailable unless future tfy --help output verifies them.

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Note

Low Risk
Documentation-only updates that adjust recommended API usage patterns (monitoring filters, metrics queries, invites/access grants) with no runtime/code-path changes.

Overview
Adds metrics-based AI Gateway monitoring guidance alongside spans tracing, including example POST /api/svc/v1/llm-gateway/metrics/query recipes (cost/tokens/latency/errors), updated filter operator enums, and time-range handling guidance.

Expands Platform access-control docs with explicit user-invite flows, clarified “invite vs grant access” sequencing, team/custom-role grant workflows, and adds virtual account/VAT management plus service-account caveats; shared API endpoint reference is updated accordingly.

Introduces capability matrices and review/confirmation gates for Prompt Registry and Skills Registry workflows, emphasizing UI vs tfy apply usage and avoiding unsupported CLI commands.

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