Add readable Locality diffs and edit history

[mohammedahmed18]

Summary

• Add Git-style readable diff rendering for loc diff and interactive loc push confirmation.
• Persist anonymous linked edit metadata and readable diff snapshots in journals, and expose them through loc log --diff.
• Keep daemon push approval aligned with the CLI-approved readable diff, with docs and regression coverage.

Test Plan

• cargo test --workspace --all-targets --no-fail-fast
• cargo fmt --check
• git diff --check origin/main..HEAD