feat(compute): extended tool capability tiers

**Context:** ROADMAP.md → Security → Tool capability tiers
**Related:** #422 (HITL elevation), #429, #246

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## Component

CDK / infrastructure

## Describe the feature

Opt-in **extended** tool profile per repo: MCP servers, plugins, and additional Gateway-mediated tools beyond the default minimal surface. Enforced at **Gateway** and **Cedar policy** layers.

## Use case

Default minimal tool surface is safe but limiting. Power users need MCP integrations with explicit opt-in and policy gates—not silent expansion.

## Proposed solution

1. Blueprint flag: `tool_profile: minimal | extended`.
2. Gateway allowlist of tool names/MCP servers per profile.
3. Cedar policies for extended-only actions.
4. Audit when profile is elevated mid-task (#422).
5. Document in `docs/design/COMPUTE.md`.

## Other information

- #422 covers runtime elevation via HITL; this covers **static profile definition**.
- Pairs with **MCP supply-chain controls** (#429).
- Design context: `docs/design/COMPUTE.md`, `docs/design/CEDAR_HITL_GATES.md`.

- [ ] This might be a breaking change

Start by reading docs/design/COMPUTE.md and docs/design/CEDAR_HITL_GATES.md, then review related issues #422, #429, and #246 to separate static profiles from runtime elevation and supply-chain controls. Done means the blueprint flag, Gateway allowlist, Cedar gates, elevation audit behavior, and documentation are defined and implemented without silently expanding the default profile.

Written by the indexing model from the issue text.