Sync polish round 4: mobile suspension and portability, conflict-copy collision recovery, accessibility and recovery wording

[callumalpass]

Integrates round 4 of the overnight campaign. Every fix comes with a regression test that failed first.

• Partition recovery-copy names by replica so concurrent devices cannot claim one hosted path
• Keep async comparison results and errors bound to their reviewed plan
• Honor pause requests while sync inspection finishes
• Skip acknowledged multipart bytes without allocating discarded output buffers
• Fence coalesced schema loads against newer invalidations
• Verify conflict decisions remain held during sync in isolated visual acceptance
• Hold conflict decisions during active sync without hiding their comparison
• Fence record-cache installation against concurrent folder invalidation
• Restore popout text selections using their owning window's DOM constructors
• Close staged upload sources after failed or cancelled object transfers
• Fence renewal commits against connection retirement in other windows
• Keep disconnect unavailable until its decision or cleanup has completed
• Reconcile vault events that arrive during the initial yielded record scan
• Name the trash destination when reviewing disconnect cleanup
• Classify mobile HTTP failures even when native JSON getters throw
• Show checking sync rather than a stale success during plan inspection
• Protect the physical vault across replica changes and reauthorization commits
• Expire mirror-write echoes in linear time during bulk downloads
• Fence mutable TFile identities across asynchronous path checks
• Close settings before handing off to sync approval or setup

Validation: clean npm ci (the patch applies), npm test (411 pass, plus 10 lossless round trips), npm run lint, and npm run check:mobile.