#168 Add credential gateway with Integration Plugins

[Anonymous]

Originally created by: kalibetre

Summary

• Add a standalone credential gateway deployment (api/domains/credential_gateway/) that brokers or proxies provider credentials instead of materializing them directly into agent pods, with durable Postgres-backed audit events for every forwarded call.
• Introduce the Integration Plugin architecture (api/domains/integrations/plugins/) as the single source of truth per provider (aai-cli profile/context/policy rendering, secret-store entries, egress mode), replacing the scattered per-provider builder functions in aai_cli_artifacts.py.
• Route GitHub, Google Workspace (short-lived broker tokens), and Firecrawl through the gateway; remove Slack and Zoho as tool integrations, including their bundled aai-cli skill docs and validators.
• Add a verbose_mode field and Hermes async /v1/runs delivery path, Telegram outbound message splitting over the 4096-char limit, scoped stale-lease reclaim, and persisted DM/thread history resume for Hermes.
• Harden Hermes workspace skill discovery, PVC startup/repair, and local dev stack robustness (new dev-gateway Make target, .env.spec and Helm wiring for the gateway service, restructured Hermes CI image contract tests).
• Fix code review findings from a prior pass: gateway health response shape, test style cleanup, and Atlassian cloud URL duplication.