v0.2.1

Fixed

• Restore ordinary PDF rendering performance after 0.2.0's transparency work.
  Plain pages use RGB spans with colour converted once per paint, skip alpha
  storage and reuse identical opaque rows in a bounded cache. Images use the
  direct RGB route when equivalent. Upgrade normally; pixels, completeness,
  cache revision and strict page-image defaults stay the same.
• Allocate page alpha only when an actual non-Normal blend needs it. Replay
  once to recover earlier transparency under the same time, memory, pixel and
  operator budgets. Preserve image/stencil component clamping from 0.2.0.
• Deduplicate memory preflight snapshots while retaining copy-on-write guards
  and detecting runtime PHP memory-limit changes. Refuse extremely wide raster
  edges before their sparse cell arrays exhaust PHP's hard memory limit.

Validation

• Six owned opaque fixtures keep byte-identical RGB output to 0.2.0 and
  allocate no page-alpha, shape or offscreen planes. A fixed 1.75x budget
  against an independent in-run RGB raster reference catches the regression;
  the released 0.2.0 measures 3.35x on the same guard.
• Alternating same-process seven-run medians before/after (ms): blocks
  34.91/13.97, deck 394.88/261.96, P2 report 109.40/71.67,
  P2 text 35.57/21.01, standard fonts 176.86/120.14, sampled image
  168.91/97.53. These are within 9% of 0.1.0 or faster while retaining the
  newer allocation guards; timings are evidence, not absolute CI thresholds.
• All twelve local Quartz page/scale PNGs remain byte-identical to 0.2.0.
  No dependency, font, golden fixture or workflow is changed.