feat: add long-horizon context integrity

[douglas-grishen]

Summary

• add the public, provider-neutral @agentplat/inference-control/context-integrity entrypoint with strict content-free contracts, canonical digests and a deterministic longitudinal reducer
• add bounded CAS state, rollback/equivocation detection, sticky degradation, recovery hysteresis and state handoff continuity
• add explainable reference analysis plus conservative analyzer composition for hostile, stale, contradictory and uncertain context
• physically filter withheld entries before controlled-model providers and Portable Agent adapters are invoked
• project integrity state into role-alignment and capability-state inputs without granting role, assignment or effect authority

Safety and compatibility

• additive and opt-in; existing executors and adapters preserve their behavior when the feature is absent
• only admit and restrict items reach protected providers or adapters
• partial context requires the exact policy-allowed filter implementation binding; otherwise evaluation fails closed
• persistent state and handoff envelopes retain digests, revisions, bounded scores and reason codes, never original prompts, outputs or hidden reasoning
• missing, expired, future, rolled-back, equivocated or malformed inputs fail closed
• browser-safe and provider-neutral; no vendor SDK or Node built-in on public browser entrypoints

Validation

• pnpm run build
• pnpm run type-check
• pnpm run test:unit — 839 tests, 0 failures (1 skipped, 6 todo)
• focused context-integrity and public-catalog suite — 14 tests, 0 failures
• pnpm run audit:public — 2,436 files, no secrets or restricted terminology
• pnpm run verify:pack — 48 tarballs and 93 packed API surfaces verified through clean pnpm and npm consumers
• bounded deterministic 10,000-step state scenario

Stack

This PR is intentionally based on codex/capability-state-fusion-v1 (#95) so its diff contains only Long-Horizon Context Integrity V1. Retarget to main after #95 lands.