v1.0.0 — merged large-session perf

What

Merges dsh-fork-perf and dsh-projection-warmup into one plugin:

• zero-copy fork — fork seed reuses deep-frozen event refs (346ms → 19ms)
• fast initFor — persistence structuredClone(seed) eliminated (135ms → ~0ms)
• chunked projection warmup — cold fold 20min → 200ms on 74万-event sessions
• fork cache backfill — abandoned forks keep projection rows
• chunked materialize — fork seed serialization split into zstd frames (no 500MB string / RangeError)
• cold-session backfill (opt-in)

Install

dsh plugin --profile web add github:orangeofcarl0-sys/dsh-large-proj-perf

Supersedes dsh-fork-perf and dsh-projection-warmup (both archived). 46 tests ALL PASS.