Make trusted-peer pulls preparation-only

[lukisch]

What changed

• Replaced live trusted-peer publishing and pull --apply with a read-only validation and preparation boundary.
• Added strict v2 registry/local-policy schemas plus a deterministic no-transfer receipt schema.
• Enforced host-owned slot, schema/version, host/peer, freshness/expiry, pinned signature-reference, payload digest, known-host pin, exact remote-path allowlist, destination safety, and secret/content gates.
• Kept direct and tailscale as provider-neutral labels only.
• Updated English/German docs, protocol, templates, examples, security guidance, module metadata, and tests.

Why

The existing implementation exceeded the authorized V4 preparation scope by reading key/known-host files, publishing into the yard, and supporting live SFTP transfer. This change stops before connectivity: no peer contact, no referenced credential/key/signature reads, no file copy, no destination creation, no yard write, and no direct_pull mutation.

Impact

The stable trusted-peer-paths CLI now exposes only validate, list, resolve, and pull-plan. pull-plan returns a deterministic prepared-no-transfer receipt with executable=false. Compatibility API methods publish and pull fail closed.

Real two-host activation still requires a separately reviewed detached-signature verifier, real SSH host-key installation, server-side read-only ACL/authentication, route authorization, anti-replay state, a no-overwrite executor, negative two-host tests, and explicit activation approval.

Validation

• ruff check system_gap_master/trusted_peer_paths.py tests/test_trusted_peer_paths.py
• ruff format --check system_gap_master/trusted_peer_paths.py tests/test_trusted_peer_paths.py
• python -m py_compile system_gap_master/trusted_peer_paths.py
• python -m pytest -q — 80 passed, 1 platform skip
• Draft 2020-12 schema checks plus generated registry/config/receipt instance validation
• git diff --check
• Source scan confirms no subprocess, Popen, --apply, --output, signing/verification key-file refs, or known-hosts-file refs in the trusted-peer module

Base commit: 01a4d29eae389b461e96acfaa5cc7f8d96a98022

Implementation commit: e2ff8f700cae7ffa5e7bc9663a7df633bbae0a17

[lukisch]

Security follow-up pushed in 3839ebd. It rejects UNC/device/extended namespaces before filesystem access, blocks Windows-invalid and superscript COM/LPT aliases, binds JSON reads to one checked file identity, and replaces the vendor-specific route label with private-overlay. Verification: 22 focused tests passed; full suite 83 passed, 1 platform privilege skip; Ruff, format, compile, schema validation, and diff-check passed. Independent re-review of the exact pre-commit diff approved with no remaining P0/P1/P2. No merge performed.