heygen-clilisted

# HeyGen REST API skill HeyGen has no official CLI. The only third-party MCP on PyPI (`heygen-mcp@0.0.3`) was published anonymously and would fail `daily-supply-chain-audit`'s minReleaseAge + trust-score gates. This skill instead drives HeyGen's REST API directly via `curl`, keeping the supply-chain surface inside Walter-OS. Closes issue #41 with the CLI + skill pattern Walter-OS already uses for `hcloud`, `postgres-cli`, `forgejo-cli`, etc. ## Money-spending — operator confirmation REQUIRED HeyGen bills per second of generated video. Every `heygen_generate_video` call costs real money. The approval-gate hook classifies paid HeyGen generation as the dedicated `heygen-generate` category (see `hooks/approval-gate.sh::CATEGORY_MIN_TIER`). That category requires a high-trust agent or an explicit operator-approved path before paid generation can run. The guardrails are layered: - **Code-level**: `_heygen_preflight` requires `HEYGEN_API_KEY`; an unauthenticated call exits 2 before any HTTP request. - **Convention**: every state-changing call (`heygen_generate_video`, `heygen_generate_from_template`) MUST be preceded by explicit operator confirmation in chat per the multi-agent autonomy spec §7.1. - **Approval gate**: paid functions and direct HeyGen generation endpoints are categorized as `heygen-generate`; read-only list/status functions are not blocked by this category. Read-only functions (`heygen_list_avatars`, `heygen_get_video_status`, `heygen_list_templates`