chore(release): prepare v1.1.0 — fold [Unreleased] into [1.1.0]

Final pre-tag CHANGELOG consolidation. No source or version changes
(package.json and VERSION are already at 1.1.0).

- Merged the 22 [Unreleased] bullets (3 Added, 7 Changed, 9 Fixed,
  3 Security) from the 1.1.0-hardening MR (merged as 85685dc) into
  the existing [1.1.0] - 2026-04-23 section under matching K-a-C
  subsections.
- Deleted the superseded "Exit code 1 for partial sync failure"
  bullet from [1.1.0] Changed. The Unreleased bullet that folds in
  now correctly states PartialFailure = 12 (exit 1 is unclassified
  CLI failure only). Keeping both would have contradicted itself
  within a single release.
- Moved the translation-memory **Note** to the end of [1.1.0] Added
  so the folded-in bullets don't appear after it (the Note is a
  global caveat on the Added list, not a mid-section divider).

Ready to tag v1.1.0.

Author: sjsyrek