feat: introduce typed Assurance IR v1

[fraware]

Purpose

Introduce an additive, content-addressed semantic interchange layer between source/framework extraction and OVK verification obligations.

This is the first consolidation step toward proof-backed acceptance of machine-generated changes. It does not change any existing lane, routing decision, or merge recommendation.

What this adds

• typed principals, resources, namespaced effects, authorization guards, and protected effects
• principal/effect/resource binding constraints
• path conditions and ordered semantic paths
• durable claim candidates with origin and approval status
• per-node source provenance, extraction coverage, assumptions, and notes
• closed-reference validation across semantic objects
• canonical Assurance IR digests and tamper detection
• unit coverage for round trips, stable identity, reference closure, binding-kind integrity, and digest mismatch
• explicit documentation of the trust boundary

Non-claims

A valid Assurance IR does not prove:

• source extraction is sound or complete;
• every application path was found;
• guards dominate protected effects;
• authorized and acted-upon principals/effects/resources are identical;
• a backend proof is valid.

Those remain separate obligations.

Follow-on

The next PR should compile Assurance IR into a stronger protected_effect_integrity obligation family:

Performed(principal, effect, resource) -> Authorized(principal, effect, resource)

with principal binding, effect binding, resource binding, and guard/path obligations independently visible.

Release isolation

This PR is intentionally draft-only while the current v1.3.0-rc.1 release-integrity work remains unresolved. Merging feature work into main would change the release candidate identity and require the exact-head release evidence to be regenerated.