~anthropic/claude-sonnet-latest → B (63:37)

Side B fixes a real correctness/perf bug (scan was replaying full rank-centrality per ingest, now a fast single-pass parse check), surfaces actual parse_error detail instead of a vague reason, and adds a genuinely useful --ingest single-event replay feature with tests. Side A is largely a deletion of a complex-but-working keystroke parser graph and its dedicated race-condition test in favor of a much simpler paste-and-go textarea, which is defensible simplification but net removes substantial tested functionality without adding comparably durable new capability.