feat(operation): complete operation v2 foundation

[jackieismpc]

Summary

• Complete the OL-02 to OL-04 operation v2 foundation on the version-frozen 0.22.14 surface.
• Add copy-first, transactional v1-to-legacy migration and the canonical v2 SeaORM schema/entities.
• Add canonical RepoViewV2 / facet codecs with fail-closed closure and restore validation.
• Add OperationStoreV2 journal persistence, monotonic journal phases, multi-parent operation writes, generation-aware head CAS, and sibling-preserving head merge.
• Keep active v1 operation logging on the legacy_* namespace until the OL-09/OL-15 cutover; no dual write, no change-id commit headers, no release/tag changes.

Validation

• cargo +nightly fmt --all --check
• LIBRA_SKIP_WEB_BUILD=1 cargo clippy --all-targets --all-features -- -D warnings
• OL-02 schema/migration tests, OL-03 facet/view tests, OL-04 operation DAG/store tests
• Existing migration, operation service/wrapper, worktree isolation, schema-upgrade, and upgrade tests
• Full cargo nextest run --all --no-fail-fast --retries 2: 9429/9430 passed, 3 skipped; the remaining agent_bridge_span_test failure was isolated and passed on a focused rerun with retries.

Related to #452.