feat: add governed Claude Agent SDK reference adapters

[rivendale]

Closes #6.

Summary

• adds equivalent Python and TypeScript one-shot reference adapters around the official Claude Agent SDK
• compiles shared pwcli intent/runtime/redaction fixtures and emits schema-validated, content-minimized receipts
• exposes only Read/Glob/Grep with explicit approval, hooks, deny policy, canonical cwd confinement, and no agent-tool network surface
• blocks absolute/traversal/home/sensitive/symlink-escape paths and treats repository output as quoted untrusted data
• supports only documented API-key/cloud authentication; no Claude subscription-token extraction or proxy guidance
• disables TypeScript session persistence and isolates Python SDK transcripts in a deleted per-run config directory
• adds pinned-SDK package/type checks, Python wheel packaging, and a clean production dependency audit

Validation

• npm run validate (spec + 9 Python + 9 TypeScript tests)
• nested npm run typecheck
• npm audit --omit=dev (0 vulnerabilities)
• Python wheel build + isolated install against claude-agent-sdk==0.2.128
• TypeScript options checked against @anthropic-ai/claude-agent-sdk==0.3.220
• git diff --check

Adversarial review

An independent adversarial reviewer found and reproduced cwd-escape/symlink reads, broken Python wheel packaging, missing pinned-SDK CI, transcript-retention drift, unused fixture contracts, and receipt-schema gaps. All findings were fixed. Final re-review reported no remaining release blockers.