[codex] Hosted review phase 5 secrets sync and retention

[romgenie]

Hosted Review Phase 5 PR Notes

Linked issues

Fixes OpenCoven#102.
Fixes OpenCoven#103.
Fixes OpenCoven#111.
Fixes OpenCoven#109.

Summary

• Enforces high-confidence secret scanning before hosted session-memory persistence or candidate creation, settings sync upload, team-memory upload, and team-memory pull apply.
• Blocks secret-bearing memory by default and records only scanner labels/reason codes, never matched secret values.
• Adds structured hosted team-memory sync scope with tenant id, installation id, repo id, repo full name, and domain metadata.
• Replaces server-wins team-memory pull application with conflict-aware handling that preserves local changes and writes conflict records for both-changed cases.
• Adds lifecycle metadata support for retention_class, redacted_at, and deleted_at.
• Excludes deleted hosted memory, redacts hosted prompt content for redacted entries, and adds helpers for deleting a hosted memory scope or redacting a memory file.
• Documents retention, redaction, secret scanning, and conflict workflows.

Test evidence

• cargo fmt --all -- --check
• cargo check --workspace
• cargo clippy --workspace --all-targets -- -D warnings
• cargo test -p claurst-core --lib claudemd --quiet
• cargo test -p claurst-core --lib team_memory_sync --quiet
• cargo test -p claurst-core --lib settings_sync --quiet
• cargo test -p claurst-core --lib memdir --quiet
• cargo test -p claurst-query session_memory --quiet
• cargo test -p claurst-core --lib --quiet
• cargo test --workspace --quiet

Risk notes

• Hosted server authorization still must be enforced server-side; the client now sends structured scope metadata but does not treat client-side path construction as an authorization boundary.
• Conflict records preserve local and remote memory text for operator review, so downstream tooling should apply the same access controls as memory storage.
• Secret scanning is intentionally high-confidence and blocks by default; false positives require operator edit/redaction before retry.