chore: bump version to 2.2.0

[DeepDiver1975]

Cuts the 2.2.0 minor release. Dated 2026-07-27 to allow weekend translation syncs to land before the release is tagged.

Changes

• Bump appinfo/info.xml version 2.1.2 → 2.2.0
• Promote CHANGELOG.md [Unreleased] → [2.2.0] - 2026-07-27, add fresh empty [Unreleased], update compare links

Included since v2.1.2

• Added: empty-state placeholder in the content pane when no note is selected (feat(ui): show empty state when no note is selected #552)
• Fixed: unfavoriting a note no longer returns HTTP 500 (fix(favorite): avoid 500 when unfavoriting a note with no tags left #554); restore empty AngularJS hash prefix for sidebar links (fix(security): upgrade vendored JS libs to patched versions #551)
• Security: upgrade vendored JS libs — underscore, angular, prism — to patched versions (fix(security): upgrade vendored JS libs to patched versions #551)

Before merging (Mon 2026-07-27)

• Rebase onto latest master so weekend translation commits are included in the release.
• After merge: tag v2.2.0 and package (make dist / make appstore, signed).

🤖 Generated with Claude Code

[DeepDiver1975]

Added a translation backfill commit: all 69 language catalogs in l10n/ are now complete for every source string, including the two new empty-state strings ("No note selected", "Create a note using the + button in the sidebar.") introduced by this release, which were previously untranslated in every language.

Each <lang>.js/<lang>.json pair was validated: valid JS/JSON, identical translation maps, exactly the canonical key set, and plural array lengths matching each language's nplurals. Existing human translations were preserved verbatim; a stale truncated key (Note is currently saving. Leaving ) was cleaned up in az/ca/sk_SK.

Related: #558 retires the Transifex sync (translations now maintained in-repo) and #557 adds an agents.md rule requiring translations to accompany source-string changes.