feat(adapter/goose): Block's Goose agentic CLI skill runtime

**Goal:** Bring Block's Goose to feature parity with Claude Code as a skill runtime. Grounds: [RFC-AI-0004 Principle 3 — Vendor neutrality](../tree/main/docs/rfcs/RFC-AI-0004.md).

**Why Goose:** Fully open-source (Apache 2.0), backend-agnostic (Claude, GPT, Gemini, OpenRouter, local LLMs via Ollama), first-class MCP support, mature recipe / extension system. Goose is one of the strongest open-source agentic CLIs for adopters who want a fully-OSS stack — no vendor CLI in the dependency tree.

**What "parity" means:**

- Skills under `.claude/skills//SKILL.md` are invokable as Goose recipes
- The `tools/*` bridges are reachable (Goose's `developer` extension covers shell commands directly)
- Sandbox parity: Goose has its own permissions model + supports running under external sandboxes; map to the framework's `bubblewrap` baseline
- HITL primitives: Goose supports per-action confirmation modes — verify and document

**Suggested approach:**

- Map `SKILL.md` → Goose recipe format (Goose recipes are YAML / Markdown describing a workflow)
- Reuse the framework's MCP servers where Goose supports them — Goose has strong MCP coverage
- Validate against the eval suite ([`tools/skill-evals/`](../tree/main/tools/skill-evals/)) — Goose's multi-model nature makes it useful for cross-model validation

**Reference:**

- RFC-AI-0004: [`docs/rfcs/RFC-AI-0004.md`](../tree/main/docs/rfcs/RFC-AI-0004.md)
- Goose: https://github.com/block/goose
- Goose recipes: https://block.github.io/goose/docs/guides/recipes/
- Existing skill shape: [`.claude/skills/`](../tree/main/.claude/skills/)