Resume thread history projection from its SQLite checkpoint

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Resume thread history projection from its SQLite checkpoint

Why

Thread history JSONL is the durable source of truth, while SQLite is a rebuildable view. If a SQLite projection fails after a durable append, the next write must catch up the unprojected suffix instead of skipping it.

What changed

• Start materialization at the byte offset stored in thread_history_projection_state.
• Project only complete newline-terminated rollout records, leaving a trailing partial record for a later pass.
• Preserve validation for missing files, invalid offsets, and missing or out-of-order ordinals without advancing projection state.

Testing

Add coverage for catching up after projection failure, avoiding replay when already synchronized, retaining partial lines, and rejecting invalid suffixes without changing SQLite state.