docs: refine changelog for v2026.4.337 and v2026.4.336}
- Replace placeholder release note for v2026.4.337 with detailed entries covering key export/import, batched pipeline imports, drag-and-drop group header reordering, auto-theme cookie fix, command palette stacking fix, info page links, and README updates - Clarify v2026.4.336 entries: specify drag-and-drop applies to connections within groups, detail keyboard shortcuts (Ctrl+D, command palette) - Remove duplicate or misplaced entries from v2026.4.336 (Redis Commands button, free enterprise tier, flat list divider fix, TTL pipeline removal, README docs line) - Remove accidental editorial commentary left in the changelog