feat(reasoning): implement provider-neutral invocation foundation

[adamshen1007]

Summary

• add strict provider-neutral Reasoning Invocation, Capability, Execution Policy, Result, evidence, and durable ledger contracts
• verify one exact Milestone 12 Delivery transaction before deterministic fake-provider execution
• enforce idempotency, immutable attempts, retry, timeout, cancellation, output budgets, and independently verifiable Consumption Evidence
• add an append-only local execution-evidence adapter with CAS, atomic head, recovery, integrity verification, and non-authoritative indexes
• add 63 independently executable evaluation scenarios and ADR/documentation updates

Verification

• pnpm format:check
• pnpm lint
• pnpm typecheck
• pnpm build
• pnpm test — 719/719 passed
• git diff --check
• independent whole-branch review — GO, zero Critical/Important/Minor findings

Scope

No real provider, network execution, credentials, streaming, tools, Agents, Hermes, MCP, distributed persistence, semantic retrieval, embeddings, ranking, graph persistence, or UI are introduced.