Refactor plugin/CLI to use a decision queue instead of single-mode UI #604

Problem

The plugin UI uses a single mode field (idle | syncing | conflict_resolution | delete_confirmation | ...) to control what's shown to the user. The CLI coordinator blocks with Promise.all() until the plugin responds to each decision prompt.

This means every combination of concurrent user decisions (delete during conflict resolution, rename during delete confirmation, etc.) needs a bespoke transition path. The huntercaron/sync-during-conflict branch alone required 5+ commits to navigate mode interactions, and automated reviewers keep flagging plausible-sounding deadlock concerns because the architecture is non-obvious.

Proposed solution: decision queue

Replace the single mode with a FIFO decision queue on the plugin side. The UI renders the front item; sync continues independently in the background.

State:
  pendingDecisions: [
    { id: "conflict-batch-1", type: "conflict", data: [...] },
    { id: "delete-Other.tsx", type: "delete",   data: [...] },
  ]
  activeSyncState: "idle" | "syncing"

Plugin changes

• Remove mode-based rendering; render based on pendingDecisions[0]
• pending-deletes → push delete decision onto queue
• conflicts → push conflict decision onto queue
• User resolves front item → shift off queue, auto-show next or hide

CLI coordinator changes

• Stop blocking on Promise.all() — fire-and-forget the request
• Plugin responses (delete-confirmed, conflicts-resolved) become SyncEvents handled by the state machine
• No more deadlock risk because nothing blocks

CLI state machine changes

• Remove conflict_resolution as a sync mode
• watching handles everything; pending user decisions are state, not a mode gate

Why not now

The current patching approach in huntercaron/sync-during-conflict is correct and covers the known edge cases. This refactor is the right long-term fix but touches the reducer, coordinator, and state machine across 4-5 files and needs dedicated test coverage.

Trigger

Open this if another mode-interaction bug surfaces or a new feature requires yet another bespoke mode transition bridge.