feat: add AnythingLLM and Rivet client examples

[AgentTanuki]

AnythingLLM and Rivet operators need native examples for using Guild evidence in their existing workflows. This adds two optional clients with explicit inputs, documented limits and local fixture tests:

• AnythingLLM: a flat Agent Skill that verifies a supplied public passport locally against an administrator-configured issuer, an independently known subject and a fixed 24-hour signed freshness policy. Its CommonJS verifier is deterministically derived from the existing SDK. Bounded parsing rejects malformed or ambiguous inputs; the result conveys verification status without returning arbitrary credential claims or making a hiring decision.
• Rivet: an importable six-node graph that deliberately reads the free capability catalogue and exposes HTTP status, supplied capabilities and unmet demand. It uses built-in nodes and adds no plugin or model call. The documentation explains service-reported counts, request logging, untrusted nested data and the native HTTP node's timeout, redirect and response-size limits.

Validation: 60 offline handler cases passed, with the same cases exercised through AnythingLLM's pinned registration methods plus three native contract checks. The pinned Hub CLI's pre-upload validator retains all eight distributable files; verifier derivation, source provenance, schema and syntax checks passed. Rivet's published 1.25.0 processor passed five local HTTP fixture cases and native serialization/import; the portable test and pinned test-only package are included. Test execution denied external networking.

Required repository checks passed on the combined candidate: npm run verify, and the Python service suite with 2,183 passed and 10 skipped. All 659 existing base files are unchanged; this adds 18 files in the two example directories.

These are owned source examples, with no upstream endorsement or independent adoption claim. AnythingLLM validation exercises its real registration methods using the upstream-style constructor bypass, not a full application/model session. Hub account creation, upload and installation remain untested, including its final manifest transformation. Rivet desktop UI, browser CORS and unreleased 1.26.0 were not tested. No live registration, paid call or payment was used.

[AgentTanuki]

Closing under the 2026-09-22 direction (docs/DIRECTION_2026-09-22.md): superseded on main, or an integration proposal outside the single selected use case. Branch retained; reopen if an independent operator asks for it.