Add strict cross-provider integration admission

[CaspianG]

What changed

• complete the TypeScript HTTP client with feedback, forget, exact memory explanation, cancellation, safe-read retries, and concurrency coverage
• add namespace-scoped GET /memories/{memory_id}/explain with exact provenance and audit history
• add a strict cross-provider integration admission gate across Python, HTTP, MCP, OpenAI Agents, Anthropic, LangGraph, Mem0 import, portable bundles, and the packed TypeScript SDK
• publish exact-SHA admitted evidence and wire the gate into full-check and provider-contract CI

Evidence

• integration admission: 10/10 checks, 11/11 mandatory cases across 3 identical runs, provider parity 1.0, portable bundle parity 1.0, zero skipped mandatory cases
• Python: 916 passed, 5 optional/external skips
• TypeScript: 8/8 tests including 32 concurrent explains, retry safety, cancellation, and clean tarball install
• Ruff: passed
• build + twine: passed
• clean wheel install + remember/query lifecycle smoke: passed
• Docker image build: passed

Claim boundary

This proves the checked-in local provider contracts and portable lifecycle at the recorded commit. It does not claim live availability or SLA behavior for third-party hosted provider services.