The magic-word @pxpipe directive fired unreliably and added per-request body
scanning to the hot path, so drop it entirely: removed the directive module +
its test and unwired it from transform.ts / proxy.ts / node.ts / index.ts.
transformRequest now leaves message bodies byte-identical — no per-request
directive parsing.
In its place, `pxpipe export <paths>` renders code/text to dense PNG pages via
the same SDK primitive the proxy uses, so exported pages are byte-identical to
what ships to the model. Width is locked to proxy density (--cols rejected as
an unknown option, guarded by tests) to prevent drift. Added --open to preview
the rendered pages plus a result footer (artifact summary + token-savings line).
Tests: export.test.ts 64 passed (incl. --open parse + default coverage); full
suite 589 passed / 29 files; typecheck clean.
teamchong