feat(cli): snapshot native continuation sources

[Neonforge98]

Problem

ORG2 can discover, read, and resume managed Codex/Claude native sessions, but portability work had no trustworthy source identity. Imported-history cache paths scan across profiles, normalized SessionEvent rows are lossy, and a caller-provided path would cross the account/security boundary.

Solution

• Add an internal, read-only native source snapshot inventory for managed OwnKey Codex and Claude Code sessions.
• Resolve only from the persisted managed session, exact runtime, account-scoped native-id ledger, and that account's profile root; no arbitrary path or broad cross-profile cache lookup is accepted.
• Require a quiescent session under the existing session control lock, revalidate status/PID/runtime/account/native binding, refuse symlink/path escape, and bound scans to 50,000 entries/depth 12.
• Hash the source twice with a 64 MiB ceiling, compare file identity/metadata, record the final-record and domain-separated source digests, and fail when the source changes mid-snapshot.
• Probe bounded Codex/Claude format metadata and record CLI version as parseable-only evidence. Every materialization capability remains false; same-profile resume is explicitly distinct from cross-account or cross-runtime rebase.

Potential risks

• Explicit snapshots may scan a large account profile and read a native transcript twice; limits cap the work and there is no background/idle invocation.
• Only OwnKey account-scoped Codex and Claude Code profiles are supported. Hosted profiles and other CLIs fail closed.
• This PR provides no Tauri command, writer, materializer, cloud upload, or behavior change. Rollback is git revert e26a121be.

Verification

• cargo test -p org2 native_snapshot --lib (13 tests passed)
• cargo fmt --check -p org2
• cargo check -p org2 --lib
• Commit hook: scoped cargo clippy --lib -p org2 passed
• git diff --check

Stack

Base: #957 (codex/conversation-continuation-episodes)

This read-only identity/digest layer is the precondition for transactional execution persistence and later plan/apply materialization; it does not claim session migration is implemented.

[Neonforge98]

Closing this experimental continuation stack after architecture review. ORG2 will reuse the existing full Team Session continuation path instead of shipping a parallel checkpoint/materializer system. The branch is preserved for audit; nothing from this stack should be merged.