v0.8.2

diting v0.8.2

Field-report fixes (from the 10-27 multi-store publishing run) plus the
output-pipeline batch.

Engine fixes:
- dynamic scripts: createElement → appendChild (empty) → el.src = url now
  loads — the most common loader idiom (webpack/jsonp, lazy chunk
  injection) silently no-op'd because insertion consumed the start slot
  on an empty script and the src setter never re-triggered preparation
- lazy-chunk resilience: a network-shaped failure on a dynamic script
  fetch (status 0 / 5xx) retries once after 75ms — 4xx and policy
  refusals fail fast; a transient miss on one chunk no longer kills the
  whole flow until a manual refresh
- Location part getters (origin/protocol/host/…) share one parsed URL
  per href — heavy pages re-parsed the same URL thousands of times,
  each read paying a fresh new URL() plus a document_url op round-trip

Output pipeline:
- page-set JPEG encodes fan out across the blocking pool instead of a
  serial loop (30-page deck: 2.4s of encode wall collapses to the
  slowest single page)
- video frame pump overlaps: the ffmpeg stdin write owns its own
  writer thread, so x264 backpressure no longer stalls the V8 thread
  painting the next frame
- render/encode pipelining: each band hands its rgba to the encoder the
  moment it paints (6-page A4 PDF: 20.7s → 7.3s)