Sync polish final round: cross-window rotations, remaining accessibility and recovery polish, perf handoff

[callumalpass]

Final round of the overnight campaign. Every fix comes with a regression test that failed first. One TODO test documents the open SDK/provider Unicode exclusion mismatch (merge report MP12).

• Avoid editor reloads and phantom echoes for idempotent text transforms
• Fence and advance open editors before remote writes and deletions
• Record production visual acceptance and Node 24 qualification
• Keep prior sync ages out of current approval, recovery and review states
• Guard deliberate pause precedence in isolated visual acceptance
• Assert lease error codes across native Web Locks and fallback runtimes
• Honor deliberate pauses over previous retries and avoid unconditional auto-sync promises
• Keep attachment setting labels in sentence case while preserving PDFs
• Profile selected attachments, initial download amplification and integrated UI
• Record completed upstream binary fence and atomic merge API ports
• Document excluded Greek folder upload as an expected-failing SDK policy regression
• Leave modified destination-tab keys to Obsidian's own shortcuts
• Honor portable excluded-folder aliases before adoption approval and upload
• Serialize credential rotations across windows before issuing renewal requests
• Return keyboard focus after comparison loading without overriding user navigation
• Retain text selections when existing workspace nodes move between windows

Validation: clean npm ci, npm test (429 pass, 1 documented TODO, plus 10 lossless round trips), npm run lint, and npm run check:mobile.