bug(ghosts): after a reload, a semantic replay re-mints ghosts of already-committed blocks #1233

Found in the #1228 review (reviewer A). This is a different route to the #730 duplicate, and it predates that PR.

1. A ghost is superseded and persisted.
2. The app reloads. readGhostLog drops superseded ghosts (src/main/ghostJournal.ts:265-271), so the renderer has no marker for that uuid.
3. The committed history loads.
4. A semantic replay opens the same turn and block. Codex rollout replay leaves semantic.currentTurn open (useIpcSubscriptions.ts near 2718).
5. ghostsFromSemanticTurn sees an empty slot and mints a fresh, unsuperseded ghost. The semantic handler never reconciles it against the runtime.entries already loaded.
6. 30 s after the turn clears, it orphans with an updatedAt newer than the old tail, and selectMergedEntries paints a duplicate.

Evidence: a temporary reproduction with the #1228 fixture's first 4 records gave a reduceGhostLogSansSuperseded size of 0, and then painted both the committed row and the ghost.

Evidence still needed: a recorded reload in which the replay actually re-opens a committed turn (Codex rollout replay is the suspect).

Fix direction: reconcile newly minted ghosts against the committed entries already held, for example by message.id, codexTurnId or tool-use id through the existing indexes. Alternatively, keep superseded markers in the log reduction for the current tail.

Refs #730, #1228, #1231.